CBSE Class 8 English Model Papers

CBSE Class 8 English Chapter 1 Parts of Speech

Question 1. Look at the following picture and write six to seven sentences about it. Also, discuss with your partner about each word used in the sentences in terms of parts of speech.

CBSE Class 8 English Chapter 1 Forest

Answer:

The picture shows a dense forest with tall trees, lush green leaves, and sunlight filtering through the branches. A small stream flows gently between the trees, adding to the serenity of the scene. Birds are perched on the branches, chirping melodiously. The forest floor is covered with fallen leaves and wildflowers, creating a colorful carpet. The air is fresh and filled with the earthy scent of nature. This peaceful environment is home to many animals and insects. Forests like these are vital for maintaining ecological balance.

Parts of Speech:

  1. Forest – Noun (names a place).
  2. Tall – Adjective (describes the trees).
  3. Flows – Verb (action of the stream).
  4. Gently – Adverb (describes how the stream flows).
  5. Melodiously – Adverb (describes how the birds chirp).
  6. Colorful – Adjective (describes the carpet of leaves and flowers).
  7. Fresh – Adjective (describes the air).

Question 2. Put the words in the correct category.

everybody these Cion type skip blue Rachel our want advice throw pointed t&at smart run yourselves patience did me spell himself students Sydney excellent easy woollen wtfo modern which wHi volleyball Spanish Cdina bright uie/lern trouble skiing she be

CBSE Class 8 English Chapter 1 Nouns Verbs Pronouns-Adjectives Example

Answer:

CBSE Class 8 English Chapter 1 Nouns Verbs Pronouns-Adjectives Examples

CBSE Class 8 English Chapter 2 The Noun

Question 1. Circle all the nouns in the following passage. Then sort them into the correct boxes.

Rehan couldn’t sleep at all that night. The little creature was afraid to close his eyes. Naveen might wake up at any time and point that awful, glaring flashlight directly at Rehan, who was crouched behind a pair of shoes in the open cabinet. Things had been likewise since Naveen began reading Do Not Enter The Monster Zoo, a collection of stories that portrays all the monsters as ruthless villains and twists the history of hatred to accuse creatures of committing things to people that people actually do to the monsters!

CBSE Class 8 English 2 Noun Categories Worksheets

Answer:

CBSE Class 8 English 2 Noun Categories Worksheet

Question 2. Label the objects and write their names in the correct columns, i.e., countable and uncountable.

CBSE Class 8 English 2 countable and uncountable

Answer:

CBSE Class 8 English 2 Noun Countable Uncountable Nouns Exercise 1
CBSE Class 8 English 2 Noun Countable Uncountable Nouns Exercise 2

CBSE Class 8 English Chapter 3 Pronouns

Question 1. Look at the following pictures and describe each picture using personal pronouns in both the subjective and the objective case

CBSE Class 8 English Chapter 2 subjective and objective case

Answer:

CBSE Class 8 English Chapter 2 Subjective Objective Pronouns Worksheet

CBSE Class 8 English Chapter 4 Determiners

Question 1. Look at the picture and complete the following sentences with a word from the box. Sometimes there are two possibilities.

CBSE Class 8 Chapter 4 Determiners

CBSE Class 8 English Chapter 4 patient guidelines blood donor xray

Question 1._________ patient (except patients with x-rays) must wait to be called.

Answer: All

Question 2. _____________patient who arrives 30 minutes late will have to wait until after the last patient has been seen.

Answer: Any

Question 3. There are blood tests __________ Wednesday and Friday.

Answer: On

Question 4. Nurse is speaking to the patients.

Answer: Each

Question 5. Flu vaccinations are free for people over 60.

Answer: All

Question 6. The boy on the left has broken_________arms.

Answer: Both

Question 7. There are ________________ blood tests on Mondays.

Answer: No

Question 8. There are three doctors, and _________________doctor is specialised in adifferent field.

Answer: Each

Question 9. ___________patients at the desk are carrying X-rays.

Answer: All

Question 10. ________________patients on the left are waiting to see a doctor.

Answer: All

Question 11. To donate blood, you can come on Fridays at___________time between 8 and 11

Answer: Any

Question 12.____________ person in the room is either a nurse or a patient.

Answer: Every

Fill in the gaps with ‘a’, ‘an’, ‘the’ or ‘O’ article.

Question 1. Where do you live?” “I live in___________flat in Gurugram. It’s _________nice flat, but___________rooms are too small. I like ___________big rooms, you know…” “I also live in____________flat It’s in Vasant Kunj

Answer: A; A;The;O;A

Question 2. When we got home,______________show had already started. We missed ___________beginning.

Answer: The; The

Question 3. Ramona has got____________new mobile phone. Her mother bought___________ mobile phone from downtown yesterday.

Answer: A; The

Question 4. My mother is____________journalist, and my father is___________engineer.

Answer: A; An

Question 5. I’ve never been to_________Zoo so i Have seen________________elephant

Answer: The; An

Question 6._______________vasco da gama Bridge across__________River Taugs is ____________ Longest Bridge in___________Europe.

Answer: The ;The ;The;noarticle

CBSE Class 8 English Chapter 5 The Present Tense

Question 1. Read the conversation and answer the questions.

Ridhima: I’m Ridhima Shetty. Are you Abhilash Singh?

Abhilash: Yes, I’m. Are you North Indian?

Ridhima: No. Vikas is North Indian and lives at Jaipur. I’m Marathi.

Abhilash: Oh, okay! I am from Delhi.

Vikas: Are you from old Delhi?

Abhilash: No, I’m from Karol Bagh, New Delhi. Is Jaipur a big city?

Vikas: Yes, it is a big city. Ridhima, are you from Mumbai?

Ridhima: Yes, I’m from Mumbai.

Abhilash: Are you and Ridhima students?

Vikas: I’m a student. She is an actress in television serials.

We are tourists in Goa.

Ridhima: Are you a student, Abhilash?

Abhilash: No, I’m not a student. I’m a doctor. I’m on holiday.

Question 1. Is Ridhima from Pune?

Answer: No, Ridhima is not from Pune; she is from Mumbai

2. Is Abhilash from Delhi?

Answer: Yes, Abhilash is from Karol Bagh, New Delhi.

3. Are Ridhima and Vikas tourists in Goa?

Answer: Yes, both Ridhima and Vikas are tourists in Goa.

4. Is Abhilash a lawyer?

Answer: No, Abhilash is not a lawyer.

5. Is Ridhima an actress?

Answer: Yes, Ridhima is an actress.

CBSE Class 8 English Chapter 6 The Past Tense

Question 1. Find and highlight 20 verbs in the given word search.

CBSE Class 8 English Chapter 6 Word Search Puzzle

Answer:

  1. SING
  2. HAVE
  3. SWIM
  4. EAT
  5. DRIVE
  6. WALK
  7. READ
  8. TAKE
  9. DRINK
  10. WATCH
  11. COOK
  12. CLEAN
  13. KICK
  14. WASH
  15. LISTEN
  16. PLAY
  17. MAKE
  18. RIDE
  19. TELL
  20. ASK

2. Use the verbs you found in the word search to complete the sentences below in the past continuous tense

Question 1. They weren’t______________to school today; they were__________their bikes

Answer: walking, riding

Question 2. He wasn’t______________a fime; he was __________a book

Answer: riding; reading

Question 3.I was not _________________dinner at home; I was___________dinner at a restaurant

Answer: reading, eating

Question 4.She was ______________ to work; I was____________the bus

Answer: driving; taking

Question 5.We weren’t ________________tea; we were____________cakes

Answer: drinking; making

Question 6.He was not __________the house; he was __________his clothes.

Answer: cleaning ; washing

Question 7. They weren’t____________to music; they were______a song.

Answer: listening ;singing

Question 8. She wasn’t____________the drums; she was________the door

Answer: kicking ; knocking

Question 9. He wasn’t ____________in the sea; he was____________a sandcastle.

Answer: swimming;making

Question 10. I was not ________________ him to do it; I was________him.

Answer: Telling; asking

3. Fill in the sentences with the past perfect continuous tense form of the verbs given in box, and then match the sentences to the picture.

CBSE class 8 chapter 6

CBSE Class 8 English Chapter 6 add pictures later

Question 1. Jim _______________ at the stars before he went to bed.

Answer: had been looking

Question 2. How long __________________ the child ________________before his dad picked him up?

Answer: had ; been crying

Question 3.Sam_____________for three hours before we me

Answer: had been sleeping

Question 4.Jatin____________a shower for half an hour before the telephone rang

Answer: had been having

Question 5. Raman said he_______________to our conversation

Answer: had not been listening

Question 6. Before the kids went outside, they____________for two hours.

Answer: had been colouring

Question 7. ___________ the littel girl ____________ the Booklet before the

Answer: Had; been painting

Question 8. ______________Jason____________ the meal for hours before the guests arrived

Answer: Had; been cooking

Question 9. Granny _________________a picture for some days she showed it bone to me.

Answer: had been painting

Question 10. Before Pete played, he _________ the net for an hour.

Answer: had been surfing

CBSE Class 8 English Chapter 7 The Future Tense

The fortune teller is predicting the future to these people. Look at the pictures and fill in the blanks with the correct form of verbs. Also, write the corresponding number of the sentence in the picture to match them appropriately.

CBSE class8 english chapter 7

CBSE Class 8 English Chapter 7 Future perfect tense (2)

Question: 1. Sohit__________ with a very attractive woman

Answer: Split will become

Question: 2.The Guptas _____________a new house in the countryside.

Answer: will buy

Question: 3.I have got bad news for you. Somebody_________ your car this year.

Answer: will steal

Question: 4.Bijoy___________a world record at Olympic Games.

Answer: will break

Question: 5.Somebody_________you a puppy next month

Answer: will give

Question: 6.Mr John____________a lot of money at a casino.

Answer: will lose

Question: 7. Gayatri ______________the Miss World beauty contest.

Answer: will win

Question: 8. Jessica_____________around the world.

Answer: will travel

Question: 9. Alice_________books. She’ll be very popular

Answer: will write

Question: 10. Simon ___________ the army next month.

Answer: will join

2. Write your questions for the fortune teller. Then work with a friend. One is fortune teller, the other one asks questions. Practise the dialogue and write the fortune teller’s predictions Fortune Teller Activity: Questions and Predictions

Instructions:

Partner A (Questioner): Ask the fortune teller 5-10 questions about your future.

Partner B (Fortune Teller): Answer with predictions using future tense (will/won’t + verb).

Switch roles and repeat!

Example Questions & Predictions

Fortune Teller (Predictions)

Question 1. “Will I become rich?”

Answer: “You will become rich, but not before you turn 30!”

Question 2. “Will I travel to another country next year?”

Answer: “Yes! You will travel to Japan next summer.”

Question 3. “Will I meet someone famous?”

Answer: “Hmm… you won’t meet a celebrity, but you will make a talented new friend.”

Question 4. “Will I pass my exams?”

Answer: “If you study hard, you will pass with excellent grades!”

Question 5. “Will I get a pet soon?”

Answer: “I see a small dog in your future… you will adopt one next winter.

3. Fill in the blanks using the future continuous or the future perfect tense form.

CBSE Class 8 English Chapter 7 Future perfect tense

Question 1. Next week, while you are working hard at the office, I __________in the sea

Answer: will be traveling

Question 2.Mr Ghosh______________his daughter’s letter by the time his wife returns home

Answer: will have chosen

Question 3.When I arrive home, my mother ____________ on her treadmill

Answer: will be running

Question 4. When Jayanti arrives home, we _ to give her a surprise

Answer: will be ready

Question 5.Before the end of the year, Bob and his wife_ all the money they won.

Answer: will have told ; was spent

Question 6.I can’t use my computer this afternoon because a technician ____________ it

Answer: will be repairing

Question 7. Tomorrow I can’t go to the cinema. I____________my grandmother at hospital.

Answer: will be visiting

Question 8.By the end of the year, Paul_____________a job as a secretary in his

Answer: will have become

Question 9.Before next summer, John ____________ enough money to go on holiday.

Answer: will have saved

Question 10.It’s been raining for a long time. I hope the Sun ________when I get up tomorrow

Answer: will have stopped

Question 11. I am sure Karan _ in the maths test tomorrow. He will be punished by the teacher.

Answer: will be chatting

Question 12. In a few months, the police_____________dangerous criminal.

Answer: will have caught

CBSE Class 8 English Chapter 8 Models

Look at the following pictures and read the sentences given below them. Then, match the sentences which express the idea or action for each picture.

CBSE Class 8 English Chapter 8

CBSE Class 8 English Chapter 8 Suggest appropriate names

Question 1. General Ability

Answer: “He can ride a bicycle.”

Question 2. Deny Permission

Answer: “You can’t go to the party.”

Question 3. Obligation (Prohibition)

Answer: “You mustn’t smoke here. It is forbidden.”

Question 4. Possibility

Answer: “It’s very cold. It may snow.”

“If you played, you might win a lot of money.”

Question 5. Asking Permission/Request (Polite)

Answer: “May I go to the toilet?”

Question 6. Absence of Obligation

Answer: “It’s Sunday. He doesn’t have to get up early.”

Answer: “You needn’t pay for the pizza. It’s free.”

Question 7.Advice

Answer: “You should brush your teeth after every meal.”

“You shouldn’t smoke. It’s bad for your health.”

“The lights went out. You ought to light a candle.”

Question 8. Request

Answer: “It is raining. Will you lend me an umbrella?”

Question 9. Past Habit

Answer: “I would go to the beach when I was a little girl.”

Question 10. Obligation (Necessity)

Answer: “You must do your homework.”

“He has a toothache. He has to go to the dentist.”

Question 11. Offer

Answer: “Shall I help you carry your luggage?”

Question 12.Certainty

Answer: (No direct example; implied in sentences like “It must be true.”)

2. Perform this activity with your partner. Read the following sentences with a blank and give options to your partner. Your partner will have to choose the correct option

Question 1. If you’re in a temple, you____________speak loudly

  1. have to
  2. mustn’t
  3. should

Answer: mustn’t

Question 2. Don’t forget to take an umbrella. It________ rain letter

  1. might
  2. must
  3. should

Answer: might

Question 3._______________ I wear jewellery to school?

  1. Should
  2. Shall
  3. May

Answer: May

Question 4. Shalini ___________ be ill. I’ve just seen her playing

  1. can’t
  2. can
  3. has to

Answer: can’t

Question 5. We________chew Gum in class.

  1. should
  2. must’take

Answer: mustn’t

Question 6.You ______________be hungry. You’ve just eaten lunch

  1. can’t
  2. might
  3. can

Answer: can’t

Question 7. I’ve just bought a lottery ticket. I____________become rich soon

  1. have to
  2. need to
  3. must

Answer: must

Question 8. Mr Gautam_________be away this weekend, but we’re not sure

  1. may
  2. might
  3. ought to

Answer: might

Question 9. Rajeev has finally got the job. He____________ be really pleased.

  1. must
  2. could
  3. can

Answer: must

Question 10. Mom____________do the shopping. Dad has already done it

  1. has to
  2. needs to
  3. doesn’t need to

Answer: doesn’t need to

Question 11. Niti couldn’t find her car keys. They_____________be in her bag

  1. may
  2. could
  3. couldn’t

Answer: could

Question 12. Piyush __________________ be at home. His car is outside

  1. may
  2. mustn’t
  3. must

Answer: must

Question 13. You__________vacuum the carpet. Raju already cleaned the room

  1. can’t
  2. should
  3. don’t have to

Answer: don’t have to

Question 14. He_______________ speak Spanish fluently. He’s been there for only a week.

  1. can
  2. can’t
  3. mustn’t

Answer: can’t

Question 15. Whose pen is it? I’m not sure. It__________be Sandra’s

  1. might
  2. can
  3. must

Answer: might

Question 16. Where can I find Vyom? ‘He_____________be in the garden.

  1. ought to
  2. may
  3. must

Answer: must

CBSE Class 8 English Chapter 9 Verbs – Non-Finites

1. Choose and circle the correct participle form in each sentence given below. Also, match the description with the picture.

CBSE Class 8 English Chapter 9 sentence description

Question 1. Sunidhi did a lot of housework yesterday. She was really tired/tiring when she finished.

Answer: Tired

Question 2. In my dream last night, I saw a frightened/ frightening monster.

Answer: frightened

Question 3. Sushmita felt very excited/exciting when her v parents took her to the amusement park.

Answer: Excited

Question 4. Mr Parekh gets bored/boring after driving in a traffic jam for a long time.

Answer: bored

Question 5. Being a mechanic is a tired/tiring job. You must be strong and patient to work as a mechanic.

Answer: Tiring

Question 6. John looked exhausted/exhausting after he spent some time in the gym.

Answer: exhausted

Question 7. Mr Jacob seemed shocked/shocking when he heard that his wife had an accident.

Answer: shocked

Question 8. The film was really excited/exciting, so Ritu and Jai watched it twice.

Answer: exciting

Question 9. Mr Dev is feeling relaxed/relaxing after a lot of work.

Answer: relaxed

Question 10. Nobody wants to listen to Dushyant because ‘ he is a bored /boring man

Answer: boring

CBSE Class 8 English Chapter 10 Active and Passive Voice

Neelima is a Bengaluru-based student who lives in a Park Street apartment. When she returned home from college in the afternoon, she discovered that her room had been broken into.

You were one of the officers that responded to her plea for assistance. Examine the image and create a composition describing what occurred in the room.

Remember to use the sentences both in active and passive voice. Then, ask your partner to categorise the sentences both in active and passive voice separately.

CBSE Class 8 English Chapter 10 Burglarized Apartment Room

Active Voice (Subject performs the action):

  1. The thief smashed the window to enter Neelima’s room.
  2. He scattered her books and papers across the floor.
  3. Neelima reported the incident to the police immediately.
  4. The officers collected fingerprints from the broken drawer.

Passive Voice (Subject receives the action):

  1. The window was smashed by the thief to gain entry.
  2. Neelima’s books and papers were scattered across the floor.
  3. The incident was reported to the police by Neelima.
  4. Fingerprints were collected from the broken drawer by the officers.

Task for Partner:

Categorize these sentences into Active and Passive Voice:

  1. The thief stole Neelima’s laptop. (Active)
  2. The jewelry was hidden under the bed by Neelima. (Passive)
  3. The police questioned the neighbors. (Active)
  4. A suspicious footprint was found near the window. (Passive)

CBSE Class 8 English Chapter 11 Adjectives- Degrees of Comparison

Read the following story and fill in the blanks with the correct form of adjectives given below.

CBSE Class 8 English Chapter 11

Question 1. Once upon a time, two brothers named Ed and Ted always competed against each other. No matter how hard Ted tried, Ed always did everything__________________
Answer: Better

Question 2. Ed was one year_________his brother Ted. And when they measured their heights, Ed was always one foot ___________ his brother.

Answer: older, taller

Question 3. They loved kicking the soccer ball, but Ed always kicked the ball_____________ his brother Ted no matter how hard Ted tried. When they played basketball too, Ed always jumped________________ his brother too. Finally, Ed was always a couple of seconds _____________Ted when they ran to the finish line

Answer: farther,higher, faster

Question 4. Ted was going to give up on being the__________because his brother was always_________________ than everything he did.

Answer: best, better

Question 5. Ed and Ted were both exhausted. Their mom called them back into the house for dinner. They sat down at the table, but Ted was__________________ his brother because he ate his whole meal.

Answer: better

Question 6. At that point, both boys realised that you couldn’t be ____________at everything than your brother in life

Answer: better

2. Look at the following pictures and describe each picture using the adjectives given below them. You can use any degree of adjective.

CBSE Class 8 English Chapter 11 pictures and adjectives

Question 1. Strong

Answer: The weightlifter is strong, but his coach is stronger, and the champion is the strongest of all.

Question 2. Frightened

Answer: The child looks frightened, the dog seems more frightened, but the cat is the most frightened by the thunderstorm.

Question 3. Poor

Answer: The beggar is poor, the homeless man is poorer, but the orphan in the war-torn country is the poorest.

Question 4. Desperate

Answer: The man searching for water appears desperate, the lost hiker looks more desperate, but the trapped miner is the most desperate.

Question 5. Happy

Answer: The baby is happy, the couple is happier, and the grandparents are the happiest at the family reunion.

Question 6. Hungry

Answer: The student is hungry, the marathon runner is hungrier, but the starving child is the hungriest.

Question 7. Proud

Answer: The artist is proud, the scientist is prouder, and the soldier receiving a medal is the proudest.

Question 8. Fat

Answer: The house cat is fat, the raccoon is fatter, but the bear is the fattest of them all.

Question 9. Beautiful

Answer: The garden is beautiful, the sunset is more beautiful, but the mountain view is the most beautiful.

Question 10. Exhausted

Answer: The worker is exhausted, the nurse is more exhausted, but the firefighter after a 24-hour shift is the most exhausted.

Question 11. Doubtful

Answer: The student is doubtful, the investor is more doubtful, but the scientist questioning a theory is the most doubtful.

Question 12. Ill

Answer: The child is ill, the elderly woman is more ill, but the patient in the ICU is the most ill.

Question 13. Cold

Answer: The morning is cold, the winter night is colder, but the Arctic storm is the coldest.

Question 14. Healthy

Answer: The apple is healthy, the salad is healthier, but the homegrown organic meal is the healthiest.

Question 15. Funny

Answer: The clown is funny, the comedian is funnier, but the grandfather’s jokes are the funniest.

Question 16. Religious

Answer: The monk is religious, the priest is more religious, but the hermit is the most religious.

Question 17. Eager

Answer: The puppy is eager, the child on Christmas morning is more eager, but the athlete before the Olympics is the most eager.

Question 18. Generous

Answer: The neighbor is generous, the philanthropist is more generous, but the anonymous donor is the most generous.

Question 19. Delicious

Answer: The bread is delicious, the cake is more delicious, but Grandma’s homemade pie is the most delicious.

Question 20. Lazy

Answer: The cat is lazy, the sloth is lazier, but the teenager on summer vacation is the laziest.

CBSE Class 8 English Chapter 12 Adverbs

1. Make two teams and perform this activity. One student from each team will have to come to the board to write a story. As she/he writes, he must use several adverbs and adjectives to make the story most interesting.

The students from each team will recognise adverbs and adjectives in the opposite team’s story. Write each word you add in the adverb or adjective list based on how it is used in the text. The team whose members identify the adverbs and adjectives more correctly, will win.

Answer : 

Adverb/Adjective Story Challenge

Objective: Teams compete to write stories packed with adverbs/adjectives, then identify them in the opponent’s story. The most accurate team wins!

Setup (5 minutes)

1. Divide the class into Team A and Team B.

2. Assign roles:

1 Writer per team (writes the story on the board).

3-4 Identifiers (spot adverbs/adjectives in the opponent’s story).

1 Judge (teacher or selected student verifies answers).

Rules & Gameplay

1. Story Writing (5 minutes/team):

Each team writes a 5-sentence story on the board.

Must include:

5+ adverbs (e.g., suddenly, loudly, carefully).

5+ adjectives (e.g., spooky, golden, exhausted).

Identification Round (3 minutes/team):

Opposite team underlines adverbs/adjectives in the rival’s story.

1 point per correct guess; -1 for incorrect guesses.

Winning:

2. Read the following sentences. If the highlighted word is an adjective, write ADJ, and if it is an adverb, write ADV.

Question 1. The cheese on this cracker tastes strange.___________________

Answer: ADJ

Question 2. I go to the gym regularly.___________________________

Answer: ADV

Question 3. She gazed at me with empty eyes. __________________

Answer: ADJ

Question 4. Have you eaten an apple lately? _______________________

Answer: ADV

Question 5. The dog howled wildly in its cage.__________________________

Answer: ADV

Question 6. I think that both sides are even now. ___________________________

Answer: ADJ

Question 7. The instructor arrived promptly at eight. ______________

Answer: ADV

Question 8. Our regular office hours are Monday to Friday from 9 am to 5 pm._______________

Answer: ADJ

Question 9. The teams were matched evenly._________________

Answer: ADV

Question 10. The homemade food was quite tasty__________________

Answer: ADV

CBSE Class 8 English Chapter 13 Adverbs

Question 1. Work in pairs and perform the activity. Ask your partner the following things given in the table and complete it.

Answer: 

CBSE Class 8 English Chapter 13 Student Habit Matching Worksheet

CBSE Class 8 English Chapter 14 Phrasal Verbs

1. Perform this activity in pairs. One student will read out the phrasal verb and its meaning, while the other student will read the sentence. Then, both the students will write different sentences using the same phrasal verb in their notebook.

CBSE Class 8 English Chapter 14 Phrasal Verb Household Actions Chart

 Answer:

CBSE Class 8 English Chapter 14 Common Phrasal Verbs Examples

Phrasal Verbs Pair Activity Guide

Objective: Practice phrasal verbs through collaborative sentence-building.

Setup:

Pair students (Student A and Student B).

Materials: Notebooks, printed phrasal verb table (or displayed on screen).

Step-by-Step Instructions:

1. Role Assignment (2 minutes)

Student A: Reads the phrasal verb + meaning aloud.

Example: “Put on – to place something on the stove.”

Student B: Reads the example sentence aloud.

Example: “I’ll put the kettle on for tea.

Sentence Creation (5 minutes/pair)

Both students write 2 new sentences in their notebooks using the same phrasal verb.

Example for “put on”:

“She put the soup on to simmer.”

“Don’t forget to put on your apron before cooking!

2. Look at the following words which go along with the word ‘get’ to make the phrasal verbs. Understand their meanings and fill in the blanks with suitable words.

CBSE Class 8 English Chapter 14 veryday English Idioms and Phrasal Verbs

Question 1. My brother is an early bird. He gets __________at 5 am every day.

Answer: up

Question 2. How can Sam get__________on his salary?

Answer: by

Question 3. Parul usually fails to get her jokes______________

Answer: across

Question 4. Nimit got__________his exams without any effort

Answer: through

Question 5. I’ve never got _____________with my brother-in-law.

Answer: along

Question 6.If this secret gets________you’ll be in trouble

Answer: out

Question 7. We’ve climbed the fence easily, but now we can’t get_____________

Answer: down

Question 8. You should get_____________with your homework right now

Answer: on

Question 9. The burglar got___________before we came back home.

Answer: away

Question 10. When Moly got__________________the plane, she saw all her family waiting for her.

Answer: off

Question 11. Rishabh__________________has beenThanksunemployedto his forparents’six months.help! He is getting

Answer: by

Question 12. After the concert the audience got ________and applauded for ten minuts.

Answer: up

Question 13. Can you tell me where I should get_____________?

Answer: off

Question 14. How did Meenu get____________here? She hasn’t got the key, has she?

Answer: in

Question 15. It took me two weeks to get____________the terrible flu.

Answer: over

CBSE Class 8 English Chapter 15 Structure of Sentences

1. In each of the following sentences, underline the subject once and the predicate twice.

Question 1. Fables such as “Little Red Riding Hood” have given wolves a bad reputation.

Answer: Fables such as “Little Red Riding Hood” have given wolves a bad reputation.

Subject: Fables such as “Little Red Riding Hood”

Predicate: have given wolves a bad reputation

Question 2. Ranchers in areas with wolves dislike the animals for attacking their livestock.

Answer: Ranchers in areas with wolves dislike the animals for attacking their livestock.

Subject: Ranchers in areas with wolves

Predicate: dislike the animals for attacking their livestock

Question 3. In the city lived many poor people.

Answer: In the city lived many poor people.

Subject: many poor people (Note: This is an inverted sentence; the subject follows the verb.)

Predicate: In the city lived

Question 4. Out of the woods came a bear.

Answer: Out of the woods came a bear.

Subject: a bear (Inverted structure; subject follows the verb.)

Predicate: Out of the woods came

Question 5. Just around the corner was the parade.

Answer: Just around the corner was the parade.

Subject: the parade (Inverted structure.)

Predicate: Just around the corner was

Question 6. In the fall, the leaves cover the ground.

Answer: In the fall, the leaves cover the ground.

Subject: the leaves

Predicate: cover the ground

Question 7. Their sudden appearance quickly aroused the townspeople’s curiosity.

Answer: Their sudden appearance quickly aroused the townspeople’s curiosity.

Subject: Their sudden appearance

Predicate: quickly aroused the townspeople’s curiosity

Question 8. With keen interest, the townspeople observed the prospectors’ movements.

Answer: With keen interest, the townspeople observed the prospectors’ movements.

Subject: the townspeople

Predicate: observed the prospectors’ movements

Question 9. Nobody in the town knew anything about the strangers.

Answer: Nobody in the town knew anything about the strangers.

Subject: Nobody in the town

Predicate: knew anything about the strangers

Question 10. The children’s books and backpacks were stolen while they were at lunch.

Answer: he children’s books and backpacks were stolen while they were at lunch.

Subject: The children’s books and backpacks

Predicate: were stolen while they were at lunch

Question 11. The zoo and the ice cream store are my favourite destinations.

Answer: The zoo and the ice cream store are my favourite destinations.

Subject: The zoo and the ice cream store

Predicate: are my favourite destinations

Question 12. The teacher and her assistant told the student and his parents that there would be a quiz in the next week.

Answer: The teacher and her assistant told the student and his parents that there would be a quiz in the next week.

Subject: The teacher and her assistant

Predicate: told the student and his parents that there would be a quiz in the next week

B. Work in pairs. One student will rewrite the following sentences by changing the position of direct and indirect objects. Then his/her partner will replace the indirect objects with personal pronouns.

Question 1. Grandma will cook my friends a delicious meal. Grandma will cook my friends a delicious meal.

Swapped: Grandma will cook a delicious meal for my friends.

Pronoun: Grandma will cook a delicious meal for them.

Question 2. Did Ravi bring Rahul the new book? Did Ravi bring Rahul the new book?

Swapped: Did Ravi bring the new book to Rahul?

Pronoun: Did Ravi bring the new book to him?

Question 3. Mom left Sunita with two oranges. Mom left Sunita two oranges.

Swapped: Mom left two oranges for Sunita.

Pronoun: Mom left two oranges for her.

Question 4. The teacher told the students funny stories.
The teacher told the students funny stories.

Swapped: The teacher told funny stories to the students.

Pronoun: The teacher told funny stories to them.

Question 5. Who will lend my brother some money?

Who will lend my brother some money?

Swapped: Who will lend some money to my brother?

Pronoun: Who will lend some money to him?

Question 6. Gagan gave Tarun a ride to the station. Gagan gave Tarun a ride to the station.

Swapped: Gagan gave a ride to the station to Tarun.

Pronoun: Gagan gave a ride to the station to him.

Question 7. The teacher gave the class a new project.

The teacher gave the class a new project.

Swapped: The teacher gave a new project to the class.

Pronoun: The teacher gave a new project to them.

Question 8. My mom bought my brother a new dress.

My mom bought my brother a new dress.

Swapped: My mom bought a new dress for my brother.

Pronoun: My mom bought a new dress for him.

Question 9. They bought my parents some CDs.

They bought my parents some CDs.

Swapped: They bought some CDs for my parents.

Pronoun: They bought some CDs for them.

Question 10. Tanuj showed Ms Sharma his project.

Tanuj showed Ms Sharma his project.

Swapped: Tanuj showed his project to Ms Sharma.

Pronoun: Tanuj showed his project to her.

CBSE Class 8 English Chapter 16 The Phrase and the Clause

1. Fill in the blanks with appropriate phrases

Question 1. The gift_________________________is from me.
Answer: wrapped in blue paper

Question 2.That song_______________reminds me of you
Answer: playing on the radio

Question 3. She loved him because he was a man_______________
Answer: of integrity

Question 4. Students_______________usually do well.
Answer: who study regularly

Question 5. He denied________________
Answer: stealing the cookies

Question 6. The wicked man loves__________________
Answer: causing trouble

Question 7. The poor man wanted________________________
Answer: to feed his family

Question 8. Horses prefer______________________
Answer: running in open fields

Question 9. People____________________are extremely rude
Answer: who interrupt others

Question 10. That desk______________looks nice in the dining room.
Answer: with the carved legs

Question 11. Have you ever tried__________________?
Answer: making homemade pasta

Question 12._______________________ surprises me.
Answer: Her sudden success

CBSE Class 8 English Chapter 17 Sentences – Simple, Compound, Complex

1. Read the following instructions and tick (/) the correct option

Question 1. The simple sentences in a compound sentence can be joined together with a comma and a__________________

  1. noun
  2. preposition
  3. conjunction
  4. verb

Answer:(3) conjunction

Question 2. The simple sentences in a compound sentence can be joined together with a _______________

  1. period
  2. semicolon
  3. question mark
  4. exclamation mark

Answer:(2) semicolon

Question 3. The simple sentences in compound sentences are also known as independent __________________

  1. phrases
  2. clauses
  3. words
  4. predicates

Answer: (2) clauses

Question 4. Choose the appropriate coordinating conjunction to join these simple sentences into a compound sentence.

Nitin ordered a burger,__________________Manu chose a sandwich

  1. if
  2. nor
  3. and
  4. or

Answer:(3) and

Question 5. Choose the subordinate clause in the given complex sentence When I went to the carnival, I rode on the Ferris Wheel.

  1. When I went to the carnival
  2. I went to the carnival
  3. I rode
  4. I rode on the Ferris Wheel

Answer: (1) When I went to the carnival

Question 6. Choose the subordinate clause in the given complex sentence. Varsha wrote down my e-mail address, so she would not forget it.

  1. Varsha wrote down my e-mail address
  2. my e-mail address
  3. so she would not forget it
  4. she would not

Answer:(3) so she would not forget it

Question 7. A complex sentence has one independent clause and one or more subordinate clauses.

  1. True
  2. False

Answer: (1) True

Question 8. Choose the subordinate clause in the given complex sentence. Alexander, who is fourteen years old, loves to skateboard.

  1. Alexander
  2. who is fourteen years old
  3. Alexander loves to skateboard
  4. loves to skateboard

Answer: (2) who is fourteen years old

CBSE Class 8 English Chapter 18 Noun Clauses

1. Choose the most appropriate noun phrase.

1. I was showing the tourist____________

  1. when to go home
  2. what to sell at the market
  3. How to get to the hotel

Answer:  3. how to get to the hotel

2. Mr Hari told the driver__________

  1. where to send him
  2. what to think
  3. what to do at the meeting

Answer: 1. where to send him

3. One of the players forgot

  1. when to turn up for practice
  2. how to run away
  3. where to buy shoes from

Answer:  1. when to turn up for practice

4. The chef is wondering ____________

  1. when to brush his teeth
  2. what to prepare for the important dinner
  3. how to wash the car

Answer:  2. what to prepare for the important dinner

5. The librarian told Peter________________

  1. when to start work
  2. how to lock up the place
  3. what to look out for on the road

Answer:  2. how to lock up the place

6. At the party, she showed him _________

  1. what to grow
  2. how to dance
  3. when to sleep

Answer:  2. how to dance

7. The sergeant is showing the soldier_____________

  1. what to sing at the concert
  2. when to grow his beard
  3. how to hold the rifle

Answer:  3. how to hold the rifle

8. The usher showed us___________

  1. how to take photographs
  2. where to sit
  3. when to comb our hair

Answer:  2. where to sit

9. Our teacher told us _______________

  1. what to do with the test paper
  2. how to lock up the place
  3. where to look for the survivors

Answer:  1. what to do with the test paper

10. The stewardess shows the passengers_________________

  1. when to start work
  2. where to land the plane
  3. how to fasten the seat belt

Answer:  3. how to fasten the seat belt

CBSE Class 8 English Chapter 19 Adverb Clauses

Fill In the Blanks With Appropriate Adverbs

1. He joined the army ____________

Answer: after he finished school

2. He doesn’t like anyone talking to him _____________

Answer: while he’s watching TV

3. By the time we got back ___________

Answer: the children were asleep

4. She turned off the lights_____________

Answer: before she left the house

5. They acted_______________

Answer: as if they were very excited

6. You can’t leave the room________________

Answer: until the lesson finishes

7. They bring us flowers__________________

Answer:  whenever they come for a visit

8. Wherever Julie goes,___________________

Answer:  she takes her daughter

CBSE Class 8 English Chapter 20 Short Compositions

1. Look at the following picture and write a factual description.

CBSE Class 8 English Chapter 31 factual description of super market

Answer: 

Factual Description of a Supermarket

The image depicts a large, well-lit supermarket interior with organized aisles and numerous products on display. The store features bright fluorescent lighting and clean, polished floors. Shelves are neatly stacked with packaged goods, including canned foods, cereals, and snacks, arranged in rows for easy access.

In the foreground, shopping carts and baskets are available for customers near the entrance. Several shoppers can be seen browsing the aisles, some pushing carts while others carry baskets. Staff members in uniform are visible, with one restocking shelves and another operating a cash register at the checkout counter.

The supermarket has clear signage above each aisle, indicating product categories such as “Dairy,” “Bakery,” and “Frozen Foods.” Refrigerated sections line the sides of the store, displaying fresh produce, dairy items, and chilled beverages. The checkout area includes multiple lanes with conveyor belts, digital scanners, and payment terminals.

Promotional banners and price tags are prominently displayed throughout the store, highlighting discounts and special offers. The overall atmosphere appears busy yet orderly, with a focus on convenience and efficiency for customers.

CBSE Class 8 English Chapter 21 Comprehension Passages

Read the following text and answer the questions that follow.

When another old cave is discovered in the south of France, it is not usually news. Rather, it is an ordinary event. Such discoveries are so frequent these days that hardly anybody pays heed to them.

However, when the Lascaux cave complex was discovered in 1940, the world was amazed. Painted directly on its walls were hundreds of scenes showing how people lived thousands of years ago.

The scenes show people hunting animals, such as bison or wild cats. Other images depict birds and, most noticeably, horses, which appear in more than

300 wall images, by far outnumbering all other animals. Early artist drawing these animals accomplished a monumental and difficult task. They did not limit themselves to the easily accessible walls but carried their painting materials to spaces that required climbing steep walls or crawling into narrow passages in the Lascaux complex.

Unfortunately, the paintings have been exposed to the destructive action of water and temperature changes, which easily wear the images away. Because the Lascaux caves have many entrances, air movement has also damaged the images inside.

Although they are not out in the open air, where natural light would have destroyed them long ago, many of the images have deteriorated and are barely recognizable. To prevent further damage, the site was closed to tourists in 1963, 23 years after it was discovered.

Question 1. Which title best summarizes the main idea of the passage?

  1. Wild Animals in Art
  2. Hidden Prehistoric Paintings
  3. Exploring Caves Respectfully
  4. Determining the Age of French Caves

Answer: (2) Hidden Prehistoric Paintings

Question 2. In line 4, the phrase ‘pays heed to’ is closest in meaning to_______

  1. discovers
  2. watches
  3. notices
  4. buys

Answer: (3) notices

Question 3. Based on the passage, what is the significance of the south of France?

Answer: Based on the passage, the significance of the south of France lies in its rich archaeological and artistic heritage, particularly as the location where the Lascaux cave complex was discovered.

Question 4. Early artists did not limit themselves to the easily accessible walls but carried their painting materials to spaces that required climbing steep walls. What does this indicate about them?

Answer: It indicates that the early artists were determined and skilled.

Question 5. Other images depict birds and, most noticeably, horses, which appear in more than 300 wall images, by far outnumbering all other animals. Choose another word for ‘depict’ from the words given below.

  1. show
  2. hunt
  3. count
  4. draw

Answer: (1) show

Question 6. Why was painting inside the Lascaux complex a difficult task?

  1. It was completely dark inside.
  2. The caves were full of wild animals.
  3. Painting materials were hard to find.
  4. Many painting spaces were difficult to reach

Answer: (4) Many painting spaces were difficult to reach.

Question 7. According to the passage, all of the following have caused damage to the paintings except____________

  1. temperature changes
  2. air movement
  3. water
  4. light

Answer: (4) light

Question 8. Would you like to explore new caves? Explain your opinion giving four reasons from the text.

Answer:

Opinion with reasons from the text:

Yes, I would explore new caves because:

  1. They may contain historical art (like Lascaux’s prehistoric paintings).
  2. Discoveries can reveal ancient human lifestyles (hunting scenes).
  3. Caves challenge explorers with hard-to-reach spaces (steep/narrow areas).
  4. They are time-sensitive (paintings deteriorate, so documenting them is urgent).

No, because:

  1. Fragility: Human presence can damage art (as in Lascaux’s closure).
  2. Danger: Climbing/crawling poses risks (like the artists faced).
  3. Preservation: Some caves should remain undisturbed (to prevent further damage).
  4. Limited access: Many caves are restricted (e.g., Lascaux closed in 1963).

CBSE Class 8 Science Long Answer Questions

CBSE Class 8 Science Long Question And Answers

CBSE Class 8 Science Long Answer Questions

CBSE Class 8 Science Short Answer Questions

CBSE Class 8 Science Short Questions And Answers

Chapter 1 Crop Management SAQs
Chapter 2  SAQs
Chapter 3 Coal And Petroleum SAQs
Chapter 4 Combustion And Flame SAQs
Chapter 5 Conservation Of Plants SAQs
Chapter 6 Reproduction In Animals SAQs
Chapter 7 Reaching The Age Of Adolescence SAQs
Chapter 8 Force And Pressure SAQs
Chapter 9 Friction SAQs
Chapter 10 Sound SAQs
Chapter 11 Chemical Effects Of Electric Current SAQs
Chapter 12 Some Natural Phenomena SAQs
Chapter 13 Light SAQs

CBSE Class 8 Science Short Answer Questions

CBSE Class 8 Science Multiple Choice Questions

CBSE Class 8 Science Short Multiple Choice Questions

 

CBSE Class 8 Science Multiple Choice Questions

CBSE Class 8 Science Question And Answers

CBSE Class 8 Science Question And Answers

CBSE Class 8 Science Question And Answers

CBSE Class 8 Science Very Short Questions And Answers

CBSE Class 8 Science Very Short Questions And Answers

CBSE Class 8 Science Very Short Questions And Answers

CBSE Class 8 Science Activities

CBSE Class 8 Science Activities

CBSE Class 8 Science Activities

Dental Products

Dental Products Introduction

Dental hygiene has been considered as important since long. In India poor dental health is a major problem and has been compounded by ignorance , poor literacy levels, habits like chewing of tobacco ,pan and pan masalas. In oerder to maintain dental hygiene, we have to take care of our teeth.

The teeth are accessory of digestive system. People use their teeth to bite and chew food. The long, sharp canine teeth tear up food, while the wide, flat, molar grinds mash up the
food.

It is the first step in the digestion of food. While chewing food, the tongue pushes it to the teeth and saliva helps in digestion and wets the food.

Tooth: Tooth consists of three layers of calcified tissue namely :

  1. Dentitle: Which surrounds the pulp cavity and extends through out the entire portion of tooth.
  2. Cementum : A layer covering the portion of tooth lying buried in the gum.
  3. Enamel : A white, hard material covering the portion of tooth projecting above the gum.

Vitamin A, C and D are all necessary for proper tooth formation. The deficiency of any of these can harm or affect the teeth. A number of inorganic compounds and their preparations are used in monitoring the oral and dental hygiene.

Most of them are Over-the-counter (OTC) products. Dental products include anticaries agent (dentrifices and fluoride salts), polishing agents and desensitizing agents.

Read and Learn More Pharmaceutical Inorganic Chemistry Notes

Anticaries Agent

Dental caries is the medical term for tooth decay or cavities. It is caused by specific type of bacteria. They produce acid that destroys the tooth’s enamel and the layer under it, the
dentin.

Many different types of bacteria normally live in the human mouth. They build up on the teeth in a sticky film called plaque. This plaque also contains saliva, bits of food and other natural substance.

Plaque forms most easily in certain parts. These include cracks, pits or grooves in the back teeth, in between teeth and near the gum line. Some of the plaque bacteria turn sugar and carbohydrate (starches) of the food into the acids.

The acid dissolves minerals in the hard enamel that covers the tooth crown. The enamel erods or develops spits. They are too small to set at first. But they get larger over time. Adds can also seep through pores in the enamel.

This is how decay begins in the softer dentin layer, the main body of the tooth. As the dentin breaks down, the enamel over it can collapse, forming a cavity. A mucin-rich saliva has less cleansing action on tooth and therefore, helps to the development of caries.

Poor nutrition of the infant and the mother at the time of infancy and childhood results in poor architecture of the teeth which become suspectible to the development of caries in the early age.

Dental caries can be prevented and oral and dental hygiene can be maintained with the help of dentrifices. Dentrifices are the products that enhance the removal of stains and dental plaque by the tooth brush.

The most accepted-approach to prevent caries including flossing and brushing accompanied by administration of fluoride and brushing accompanied by administration of fluoride either internally or topically the teeth.

Newer devices also have been developed to detect tooth decay. They are useful in some situations and rhey do not spread decay. The one most commonly used dental caries is a liquid dye or stain the dentist brushes the non toxic dye over your teeth,then rinse it off with water .

It rinses always cleanly from healthy areas but sticks to the decayed areas. Some dentist also use high tech devices such as layers to detect cavities. Under many conditions,these devices can detect very early tooth decay,which actually can be reversed.

Role Of Fluoride

Fluoride is anticariogenic as it replaces the hydroxyl ion in hydroxy apatite with the fluoride ion to form fluorapatite in the outer surface of the enamel. It can be administrated by two
routes- Orally and Topically.

Fluoride in low concentration (1-2 parts per million), if present in drinking water, also causes, the decrease in development of incidence of caries in the population. Fluoride can also be administrated orally as Sodium Fluoride tablets or drops added in water or fruit juice. But it is not beneficial as such.

A 2% aqueous solution of sodium fluoride and 8% solution of stannous fluoride are extensively used for topical application. Two such well established fluorides are Sodium fluoride and Stannous fluoride.

Role Of Phosphate

Inorganic phosphate salts can also be useful in the prevention of dental caries. Phosphate ions are needed for stronger bone as well as for healthy teeth. Soluble salts of phosphate
such as sodium monohydrogen phosphate, sodium dihydrogen phosphate can cause caries reduction in men. It is also used as cleansing agent.

Sodium Fluoride

Chemical Formula : NaF             Molecular Weight: 41.99

It is having not less than 98.0% of NaF and not more than 100.5% of NaF, calculated with refrence to the dried substance.

Preparation

It is prepared by reacting hydrofluoric acid with Sodium Carbonate. Sodium fluoride being not very soluble precipitates out.

SODIUM FLUORIDE

Alternatively, the another method involves the double decomposition of Calcium Fluoride with Sodium Carbonate.

SODIUM FLUORIDE

Here, insoluble calcium carbonate can be removed by filtration.

Properties

It occurs as colourless, odourless crystals or as white powder. It is soluble in water but is insoluble in alcohol. On acidification of salt solution, hydrofluoric acid is produced. This is weak acid and is poisonous. Aqueous solution of salt yields alkaline solution.

Storage

Aqueous solution of Sodium Fluoride corrodes ordinary glass bottles and hence the solution should be prepared in distilled water and stored in dark, pyrex bottles.

Pharmaceutical uses

It is used in the prevention of dental carles because ol Its lluorldo Ion concentration. tooth constituent of some insecticides and rodenllcides. It Is used In tin* preparation o a
pastes which constitutes about 75% of Sodium Fluoride and 25% of glycerol.

Usual dose

2.2 mg (equivalent to lmg of fluoride Ion)

Applications

1.5-3.0 ppm in drinking water.

Stannous Fluoride

Molecular formula : SnF2                      Molecular Weight: 156.69

Synonym: Tin fluoride

Methods of preparation

It is prepared by evaporating a solution of stannous oxide, In Hydrofluoric acid In the absence of oxygen.

Stannous fluoride is prepared by heating Stannous Oxide with gaseous hydrofluoric acid in the absence of oxygen.

STANNOUS FLUORIDE

Properties

It occurs as a white crystalline powder with a bitter saline unpleasant taste. It Is freely soluble in water; practically insoluble in alcohol, chloroform and ether. Aqueous solution
decomposes within a few hours with the formation of a white precipitate, they slowly attack glass.

Uses

It is used as a preventive for dental caries.

Dentrifices Or Cleaning Agents

A dentrifice is a substance used with a tooth brush for the purpose of cleaning the accessible surfaces of the teeth. Commercial dentrifices are available in the form of pastes and powders. Many dentrifices contain flavours and soap or detergent.

The powders and pastes contain abrasives such as Calcium Carbonate, Calcium Phosphates, Calcium Sulphate, insoluble Sodium Metaphosphate, Calcium Carbonate and Sodium Chloride.

Toothpastes contain liquids (e.g. glycerin, propylene glycol, sorbitol solution, water and alcohol) and thickners (e.g. starch, trageanth, algin and cellulose derivative). Dentrifices or tooth pastes are responsible for physically removing plaque and debris.

They may also contain some sweetening agents. Certain individual may need an abrasive containing dentrifices. The abrasive dislodges the dental plaques and helps to remove them. It should be mildly abrasive for this purpose.

Calcium Carbonate

Chemical Formula: CaC03                                              Molecular Weight. : 100.09

Synonym

Precipiated Chalk, Precipitated Calcium Carbonate. It is the most abundant and widely distributed in nature as limestone, iceland spar, olomite and shells of sea animals.

Method of Preparation

Calcium carbonate when come in contact with sodium carbonate leads to the formation of calcium carbonate and sodium chloride

CALCIUM CARBONATE

Physical Properties

Calcium carbonate occurs as a white, odourless, tasteless, micro crystalline powder which is stable in air. It is practically soluble in dilute hydrochloric acid and nitric acid but is insoluble in water and alcohol.

It dissolves in aqueous phosphoric acid & the solution on evaporation deposits crystals of calcium dihydrogen.

Assay

This is complexometric assay. The sample is dissolved in water and hydrochloric acid and a known excess of 0.1M disodium edetate is added & diluted with watewr. It is neutralised
with strong ammonia solution, ammonia buffer pH 10 and mordant black II mixture are added and the titration is continued till be change of colour from pink to full blue takes place
at the end point.

Calcon mixture consist of calcon (mordant black) and freshly ignited anhydrous sodium sulphate. It gives a purple-red colour with calcium ions in alkaline solution.

Uses

It is used externally as dentrifice, as a dental cleaning polishing agent for most tooth paste and tooth powders. It is used as insecticides. Due to its fast action, calcium carbonate is used
as an antacid, as a calcium supplement in deficiency states; as a food additive. It is also used in the preparation of homoepathic medicine.

Desensitizers

The desensitizers tend to decrease hypersensitivity of the teeth. When applied to their outer surface, especially where erosion has occurred near the gum line, they reduce the senstivity
of the teeth to heat and cold. Inorganic compounds of desensitizers are Strontium Chloride and Zinc chloride

Zinc Eugenol Cement

Zinc Oxide Eugenol (ZOE) is material created by the combination of Zinc Oxide and eugenol contained in oil of cloves. An acid-base reaction takes place with the formation of zinc
eugenol chelate. The reaction is catalyzed by water.

Advantages :

  1. Dimensional stability
  2. Good surface

Disadvantages :

  1. Eugenol allergy in some patients.
  2. Cannot be used in very deep undercuts.

Composition:

  • Liquid
    • Eugenol (react with zinc oxide)
    • Olive oil (plasticizer)
  • Powder
    • Zinc oxide (principal ingredient)
    • Zinc stearate (accelerator, plasticizer)
    • Zinc acetate (accelerator, improve strength)
    • White rosin (to reduce brittleness of set cement)

Properties

It is the cement of low strength, low abrasive resistance, and low flow after setting, so it is used for temporary filling not be more then few days.
It has adhesive effect on exposed dentin. It is least irritating than other dental cements.

Uses

  1. For temporary fillings.
  2. Pulp-capping agents.
  3. Zinc oxide eugenol is used as an antimicrobial additive in paint.
  4. It is used as an impression material during construction of complete dentures and is used in the mucostatic technique of taking impressions.

Dental Products Very Short Answer Questions

Question. 1. Define Dentrifices?
Answer. A Dentirifice is a substance used with a tooth brush for the purpose of cleaning the accessible surface of the teeth.

Question.2.Define Dental Caries?
Answer. Dental caries is the medical term for tooth decay or cavities.

Question 3. What is the role of fluoride?
Answer. Fluoride removes the anticaries as it replaces the hydroxyl ion in hydroxyapatite with the fluoride ion which form fluoroapatite.

Question 4. Does the desensitizer increase or decrease the hypersensitivity of teeth?
Answer. Desensitizer tends to decrease the hypersensitivity of teeth.

Question.5.What is the molecular formula of Dicalcium Phosphate?
Answer.CaHPO4.

Question.6.Name any two inorganic compounds which are used as dental caries?
Answer.

Sodium monohydrogen phosphate
Sodium dihydrogen phosphate

Question 7.What is the another name of sodium metaphosphate?
Answer. Sodium metaphosphate is also known as Madrell’s salt.

Question 8.How is stannous fluoride prepared?
Answer. Stannous fluoride is prepared by heating stannous oxide with gaseous hydrofluoric acid in the absence of oxygen.

SnO + 2HF- ->SnF2 + H20

Question 9. How can dental caries be prevented?
Answer. Dental caries can be prevented by using dentrifices.

Question 10. Name the two inorganic fluoride compounds used in dental products?
Answer.

Sodium fluoride
Stannous fluoride

Dental Products Fill In The Blanks

1. Dentrifices are the compounds that are used for ……………

Answer: Cleaning teeth and. gums

2. The cleaning action of dentrifices depends on their……………….

Answer: Abrasives

3. To prevent dental caries tooth paste containing………………………… should be used.

Answer: Sodium fluoride

4. Soluble salts of phosphate are ……………………..

Answer: Sodium monohydrogen phosphate, Sodium dihydrogen phosphate

5. …………………….. is a medical term for tooth decay or cavities.

Answer: Dental earies

6. Cone, of fluoride in drinking water is…………………

Answer: 1.5–3.0 ppm

7. Stannous fluoride is prepared by heating………………with …………….. in the absence of oxygen.

Answer: Stannous oxide, hydrofluoric acid

8. Chemical formula of Sodium fluoride is ……………and Stannous fluoride is………………..

Answer: NaF and SnF2

9…………….. reduce the sensitivity of the teeth to heat and cold.

Answer: Dentrifices

10. Precipitated chalk is…………………………

Answer: Calcium carbonate

Dental Products Multiple Choice Questions

Question 1. Fluoride inhibits carries formation via

  1. Downward acid solubility of enamel
  2. Bacterial inhibition
  3. Both a) and b)
  4. None of these

Answer: Both a) and b)

Question 2. Hydroxyapatite is a mixture Ca2+ salt of

  1. CO3″
  2. P04′
  3. OH
  4. All of these

Answer: All of these

Question 3. Dental caries is a medical term of

  1. Cleaning action
  2. Polishing action
  3. Tooth decay or cavities
  4. None of these

Answer: Tooth decay or cavities

Question 4. Fluoride can be administrated either

  1. Orally
  2. Topically
  3. Both a) and b)
  4. None of these

Answer: Both a) and b)

Question 5. Sodium Metaphosphate is also known as

  1. Precipitated chalk
  2. MadrelTs salt
  3. Both a) and b)
  4. None of these

Answer: MadrelTs salt

Question 6. Desensitizers tend to

  1. Downward hypersensitivity of the teeth
  2. Upward hypersensitivity of the teeth
  3. Bacterial inhibition
  4. None of these

Answer: Downward hypersensitivity of the teeth

Question 7. Example of Desensitizer is

  1. Zinc chloride
  2. Sodium fluoride
  3. Stannous fluoride
  4. Calcium carbonate

Answer: Zinc chloride

Question 8. ‘Butter of Zinc’ is also known as

  1. Zinc chloride
  2. Zinc carbonate
  3. Zinc bicarbonate
  4. None of these

Answer: Zinc chloride

Question 9. Which vitamin is necessary for tooth formation?

  1. Vitamin A
  2. Vitamin C
  3. Vitamind D
  4. None of these

Answer: None of these

Question 10. Phosphate is used as .

  1. Cleansing agent
  2. Flossing agent
  3. Removing stains
  4. All of the above

Answer: Cleansing agent

Types Of Impurities In Pharmaceutical Substances

Types Of Impurities In Pharmaceutical Substances Introduction

Pharmaceutical Chemistry is the branch of chemistry which deals with the study of medicines. It includes the main branches of chemistry namely inorganic chemistry, organic chemistry, medicinal chemistry, analytical chemistry and physical chemistry.

The term “Inorganic Chemistry” in shorter sense is called “chemistry of everything else”. It deals with the study of inorganic compounds containing their molecular weight, molecular formula, occurrence, method of preparation, physical and chemical properties, assay and uses as pharmaceutical aids, therapeutic and diagnostic agents.

It has accomplished rapid progress in understanding the properties of all chemical compounds. It is of fundamental importance not only as a basic science but also as one of the most useful source of modem technologies.

The pharmaceutical substances used in the treatment of diseases may be procured from the natural sources such as minerals, salts, purified inorganic chemicals, calcined inorganics (ash or bhasma), plants, animals, microbes and from synthetic chemicals.

In ancient times mercury, gold, copper and silver were also used in medicine. The specification for each pharmaceutical is listed in Pharmacopoeia.

Pharmacopoeia

The term Pharmacopoeia is derived from the Greek word “pharmakon” means drug or medicine and “poiein” is to make. Drugs manufactured in India have to be labelled with the mandatory non-proprietary name with the suffix “I.P”. It provides a collected list of drugs and medicinal substances along with directions for making preparation from them.

Many countries are now publishing pharmacopoeias of their own and by this they are able to control the standards of the drug produced in their countries and also the standards of the drugs imported into their countries and ensure the health of their people.

A drug or a medicinal chemical included in a pharmacopoeia is termed as official and the sections dealing with official drugs, preparation and substances are known as monograph.

Read and Learn More Pharmaceutical Inorganic Chemistry Notes

History of pharmacopoeia

Indian Pharmacopoeia (I.P.)

In India, the first pharmacopoeia had been publishes as “Bengal Pharmacopoeia in 1844.

The Government of India constituted a permanent Indian Pharmacopoeia Committee in 1948 for preparing Indian Pharmacopoeia under the chairmanship of Dr. B. N. Ghosh. The first edition of I.P. was publishes in 1955, followed by a supplement in 1960 which contains large number of crude drugs and their preparation.

List of Publication of various Edition of Indian Pharmacopoeia

 

Indian Pharmacopoeia(i.P)

Salient features of First edition of Indian Pharmacopoeia (1955):

  • Covers 986 monographs.
  • Titles of monograph in Latin language.
  • Weight and measures in metric system.
  • Doses expressed in both metric and English system.
  • List of preparations given at the end of some of the monographs.
  • Abbreviated titles used.
  • Descriptive terms used for solubility instead of exact solubility.

Salient features of Second edition of Indian Pharmacopoeia (1966):

  • Published in 1966 and its supplement was published in 1975.
  • Titles of monographs changed from Latin to English.
  • Name of drug comes first in title e.g. Aminophylline Injection.
  • Solubility expressed in parts of solvent per unit part of solute.
  • 93 new monographs were added.
  • New analytical techniques had been included.
  • Test for sterility had been modified to detect fungi.
  • ‘Usual Strength’-a heading used to represent strength of tablet had been used.
  • 214 monographs from I.P. 55 were deleted.

Salient features of Third edition of Indian Pharmacopoeia (1985):

  • Published in 1985 with two volumes and nine appendices.
  • 260 new monographs were added and 450 were amended.
  • New analytical techniques (Flame photometry,
  • Electrophoresis, Fluorometry etc.) had been introduced.
  • Dissolution had been introduced.
  • Microbial limit tests being prescribed for liquid preparation.
  • Gas liquid chromatography had been recognized.
  • Determination of viscosity have been modified involving use of Ostwald viscometer.
  • New appendix “Water for Pharmaceutical Use” had been introduced.
  • Drugs renamed and some drugs had been omitted.
  • Addendum I to I.P. 1985 was published in 1989, where 46 new monographs were added and 126 amended.
  • Addendum II to I.P. 1985 was published in 1991, where 62 new monographs were added and 110 amended.

Salient features of Fourth edition of Indian Pharmacopoeia (1996):

  • Published in 1996 under the chairmanship of Dr. Nityan and along with Dr. Parvinder Singh followed by its addendums in 2000 and 2003.
  • Contains 1149 monographs and 123 appendices in two volumes.
  • Computer generated structural formulae used.
  • Infrared and Ultra Violet absorption spectrophotometric tests for identification of drug were added.
  • Included 294 new monographs and 110 monographs were deleted.
  • High Pressure Liquid Chromatography (HPLC) had been used as analytical method.
  • Bacterial endotoxin test were introduced.
  • Quantitative method for determining particulate matter in injectable preparation being replaced by qualitative.
  • Monographs of ORS, ORS-bicarbonate had been omitted out and ORS-citrate formula had been added.
  • Specific biological assay and test were transferred to individual monographs.
  • The veterinary supplement of I.P. 1996 contains 208 monographs and four appendices.

Salient features of Fifth edition of Indian Pharmacopoeia (2007):

  • Published in 2007 followed by its addendum in 2008.
  • Presented in three volumes.
  • Volume one contains general notices, structure of IPC, Acknowledgements.
  • Volume two and three contains general monographs on dosage forms, drug substances and pharmaceutical aid.

Salient features of Sixth edition of Indian Pharmacopoeia (2010):

  • Published in 2010 followed by its addendum in 2012 and DVD of I.P. 2010 was also available.
  • Released on 27th December 2011 by Mr. P.K. Pradhan in presence of Mr. L. C. Goyal and Dr. Arun Kumar.
  • Consists of three volumes.
  • Volume one contains Notices, preface, structure of IPC, general chapters.
  • Volume two contains general monographs on dosage form, drug and pharmaceutical aid (A to M).
  • Volume three contains general monographs on dosage form, drug and pharmaceutical aid (N to Z).
  • Products of biotechnology, herbal products, and additional antiretroviral drugs were included.
  • Standards for new drug under NHP were added.
  • Microbial contamination chapter updated.
  • Chapter on NMR is incorporated in appendices.
  • New chapter on Liposomal products is also added.

Salient features of Seventh edition of Indian Pharmacopoeia (2014):

  • Published in 2014 and presented in four volumes.
  • Contain 2567 monographs of drugs out of which 577 are new monographs.
  • Introduced 19 radiopharmaceutical monographs for the first time.
  • 10 antibiotic monographs, 31 herbal monographs, 5 vaccine, and immunosera for human use, 6 insulin products and 7 biotechnological products with 19 new general chapters were included.

Salient features of Eighth edition of Indian Pharmacopoeia (2017):

The latest Edition of Indian Pharmacopoeia, IP-2018 has been released on 29th September, 2017 by Sh. C.K. Mishra, Secretary Health & Family Welfare, Govt, of India.

IP-2018 has been brought out in 4 Volumes incorporating 220 new monographs (Chemical Monographs (170), Herbal Monographs (15), Blood and Blood related products (10), Vaccines and Immunosera for Human use monographs (02), Radiopharmaceutical monographs (03), Biotechnology Derived Therapeutic Products (06), Veterinary monographs
(14)), 366 revised monographs and 7 omissions.

Salient Features of IP-2018:-

  • General Chemical tests & Thin Layer Chromatography (TLC) for identification of an article have been almost eliminated and more specific infrared, ultraviolet
    spectrophotometer and HPLC tests have been given emphasis. The concept of relying on published infrared spectra as a basis for identification has been continued.
  • The use of chromatographic methods has been greatly extended to cope with the need for more specificity in assays and in particular, in assessing the nature and
    extent of impurities in ingredients and products.
  • Most of the existing Assays and Related Substances Test methods are upgraded by liquid chromatographic in view to harmonize with other International Pharmacopoeia.
  • Pyrogen test have been replaced by Bacterial Endotoxin test (BET) in parenteral preparations and other monographs.
  • For ease of access to make Pharmacopoeia more user friendly, Index has been incorporated in Volume-I along with that already existing in Volume-IV of IP.
  • 53 New Fixed Dose Combination (FDC’s) combination monographs have been included, out of which 25 FDC monographs are not available in any Pharmacopoeia.
  • General Chapters on Volumetric Glassware, Conductivity, Dissolution test, Disintegration test, Dimensions of Hard Gelatin Capsule Shells etc. have been revised.
  • For Controlling the Microbial quality of all the medicinal product general chapter on Maintenance, Identification, Preservation and Disposal of Microorganism have been
    revised.

British Pharmacopoeia (B. P.)

British Pharmacopoeia was published by the health ministers of the United Kingdom. The first edition of B.P. was published in 1864 which consists of two parts “Materia Medica” and

“Preparation and Compound”. Australia and Canada are two of the countries that have adopted the B.P. as their national standard book. The various publication of B.P. comes out in subsequent years as under:

  • 1867: Second edition.
  • 1885: Third edition.
  • 1898: Fourth edition.
  • 1914: Fifth edition.
  • 1932: Sixth edition.
  • 1948: Seventh edition. It contains official 49 tablet preparations and official 75 injections.
  • 1951: Addendum to BP 1948 was published.
  • 1953: Eighth edition. In this title of drug and preparation was in English instead of Latin and metric system was used.
  • 1955: Addendum to BP 1953 was published.
  • 1958: Ninth edition.
  • 1960: Addendum to BP 1958 was published. It includes monographs on radioactive chemicals.
  • 1963: Tenth edition.
  • 1968: Eleventh edition.
  • 1973: Twelfth edition.
  • 1980: Thirteenth edition.
  • 1988: Fourteenth edition.
  • 1988, 1990, 1991 & 1992: Four addendums were published.
  • 1993: Fifteenth edition.
  • 2000: Sixteenth edition. It contains veterinary drugs.

The other editions were published in 2004, 2005, 2007-2009 (published in six volumes), 2010 and 2014. The current edition was published in 2015 which includes almost 3500 monographs spread out in six printed volumes.

United State Pharmacopeia (U.S.P.)

United States Pharmacopeia and the National Formulary (USP-NF) are recognized as official compendia for determining the standard of pharmaceutical products. The first USP was published in 1880 under the authority of United State Pharmaceutical Convention (USPC).

National Formulary (NF) was published first in 1888 under the authority of the American Pharmacists Association (APhP). After 1975, both USP and NF are published by USPC in a
combined volume as USP-NF.

USP-NF was published at every ten years interval from 1820-1942. But from 1942-2000, it was published at an interval of five years. After 2000, USP-NF
has been published annually. USP 40 – NF 35 will be officially released in year 2017.

British Pharmaceutical Codex (B.P.C.)

This book was prepared as a reference book for the use of medical practitioners and dispensing pharmacists. In 1903, Pharmaceutical society of Great Britain came up with BPC. The first edition of the BPC was published in 1907.

The subsequent editions were published in 1911, 1923, 1934, 1949, 1954, 1959, 1963, 1968 and 1973. From eleventh edition 1979 onwards BPC was considered as Pharmaceutical Codex only. It comprises of general monographs of drugs and also provides standards of medicaments and materials that not included in BP and British National Formulary (BNF).

Extra Pharmacopoeia (MARTINDALE)

This pharmacopoeia was first issued in 1883 by William Martindale and now it was published by pharmaceutical society of Great Britain.

Pharmacopoeial description

Practically most of the pharmacopoeia consists of three main sections namely:

  1. General notices
  2. Monographs of the official drugs
  3. Appendices

General notices: It is useful information of pharmaceutical progress since last edition as it summarizes the various changes including additions/deletions in the present edition
compared to last edition.

Monographs of the official drugs: The word “Monograph” means the written study of a subject. It is derived from a Greek word (mono=single, grapho = to write). As the medicinal substances are to be used for the cure and prevention of diseases, therefore,these are considered as very important and hence their written studies appear as monograph .

  1. Titles:- Monograph titles are in English and French in the respective versions and there is a Latin subtitle. It includes the main names of the substance.
  2. Synonyms: Common names, if any, of the substance.
  3. Chemical formula and Molecular Weight: If necessary graphic, molecular formula and molecular weight are given at the beginning of the monograph.
  4. Chemical names:- It is given in the monograph as employed by the International Union of Pure and Applied Chemistry (IUPAC). It does not constitute for the analytical standards such as UV, NMR, IR etc.
  5. Category: It indicates its use in pharmacy/medicine. It represents pharmacological action of the substance such as antifungal, antimicrobial, anti inflammatory, etc.
  6. Doses: Doses mentioned in the Indian Pharmacopoeia (I.P.) represent the average range of quantities suitable for adults.
  7. Description: This include a statement about its general physical properties , i.e. whether the substance is a liquid or solid, coloured or colourless, amorphous or crystalline, its taste, etc.
  8. Solubility: In terms of solubility the terms used have the following significance referred to a temperature between 15ÿC and 25ÿC. The term “partly soluble” is used to describe a mixture where only some of the components dissolve.
    The term “miscible” is used to describe a liquid that is miscible in
    all proportions with the stated solvent.
  9. Standards: Indian Pharmacopoeia (I.P.) prescribes the standard of purity and strength in the monograph of almost all official substances. A substance is not deemed to be of
    standard quality unless it complies with the requirements stated under ‘standard’ of its monograph.
  10. Identification: It includes some specific and non-specific test of the substance.
  11. Test for purity: Indian Pharmacopoeia (I.P.) prescribes tests for purity of almost all the offcial substances. These tests include boiling point, melting point, limit test for chlorides, sulphates, iron, aresenic, lead, heavy metals, pH of solution, loss on drying, specific optical rotation, etc.
  12. Assay: Assay is used for the quantitative determination of principal ingredients of the official substances and their preparations.
  13. Storage:-Indian Pharmacopoeia prescribes the conditions for storage in such a way as to prevent contamination and, as far as possible, deterioration. Where special conditions of storage are recommended, including the type of container and limits of temperature, they are stated in the monograph. The following expressions are used in monographs under Storage with the meaning shown.
    1. In an airtight contaitter means that the product is stored in an airtight container. Care is to be taken when the container is opened in a damp atmosphere. A low moisture content may be maintained, if necessary, by the use of a desiccant in the container provided that direct contact with the product is avoided.
    2. Protected from light means that the product is stored either in a container made of a material that absorbs light sufficiently to protect the contents from change induced by such light or in a container enclosed in an outer cover that provides such protection or stored in a place from which all such light is excluded.
  14. Labelling When the term “label” is used in the Pharmacopoeia, the labelling statements may appear on the container, the package, a leaflet accompanying the package or a certificate of analysis accompanying the article, as decided by the competent authority.

 

PHARMACOPOEIAL DESCRIPTION

Appendices: General notices and monographs are followed by comprehensive section of appendices.

Appendix- I: It describes about the apparatus needed for various pharmacopoeial tests and assays.
Appendix-ll: It describes about biological tests and assays.
Appendix-Ill: It contains details of various chemical tests and assays.
Appendix-lV: It contains details of microbiological tests and assays.
Appendix-V: It includes physical tests and determinations like loss on drying, pH determination, melting range, etc.

Appendix-Vl: It describes useful directions on cleaning glassware’s.
Appendix-VIl: It describes the reagents and solutions needed for various tests and assays.
Appendix-VIII: It describes about the reference substances.
Appendix-IX: It describes the names and symbols used in the pharmacopoeia and their atomic weights have been described.

Impurity

Impurity is defined as any substance coexisting with the original drug, such as starting material or intermediates or that is formed, due to any side reactions. Chemical purity means
freedom from all foreign materials. Purification of chemicals is expensive and therefore purifying a substance to much higher degree is necessary.

Effects of Impurities

Pure substances are difficult to get and some amount of impurity is always present in the material. So the impurities which are present in the substances may have the following effects:

  1. Impurities may lower the shelf life of the substances.
  2. Therapeutic effect can be decreased.
  3. Impurities may bring about incompatibility with other substances.
  4. Impurities may cause1difficulties during formulations and use of the substances.
  5.  Sometimes Impurities changes the chemical and physical properties of the substances.
  6. Shows toxic effect after a certain period.

Sources of Impurity:

A compound having foreign materials is said to be impure. The origin of impurities in drugs is from various sources and phases of the synthetic process and preparation of pharmaceutical dosage forms. Majority of the impurities are characteristics of the synthetic route of the manufacturing process.  The pharmaceutical preparation should be free from toxic and other impurities.

The impurities commonly found in medicinal preparations are:

  • Impurities due to which substances become incompatible.
  • Due to colouring or flavouring substances, e.g., Sodium Salicylate.
  • Humidity.
  • Chemical and physical properties.

The various sources of impurities in pharmaceutical substances are as follows:

Raw Materials Used in the Manufacturing of Pharmaceutical Process: The source of pharmaceutical substances are either natural or synthesized from chemical starting materials. It is essential to verify the identity of the source material and its quality otherwise it contaminate the final product. Example: lead and heavy metals are found as impurities in many sulphide ores, Rock salt used for the preparation of sodium chloride is contaminated with small amounts of calcium and magnesium chlorides.

Reagents employed in the manufacturing process: Pharmaceutical substances are either isolated from natural sources (mineral sources, plants, animals and microbes) or synthesized from chemical starting materials. If reagents are employed in the manufacturing process are not completely removed by washing, these reagents may be present in final products.
Example: e.g., Magnesium impurities are found in calcium minerals, aluminum ores are usually accompanied by alkali and alkaline earth compounds.

Solvents: Water is the most commonly used solvents in the preparation of inorganic pharmaceuticals. Different types of water containing different types of impurities. Various types of water are:

Tap water: Containing impurities of Magnesium, sodium, calcium, chloride, sulphates and carbonates. +

Softened water: It is prepared from tap water nut it contains more of sodium and chloride ions as impurities.

Demineralized water: It is prepared by ion exchange and it is free from Magnesium,sodium, calcium, chloride, sulphates and carbonates impurities. It contains pyrogens, bacteria and organic impurities.

Distilled water: This water is free from all inorganic and organic impurities. It is best solvent for pharmaceutical preparations.

Action of reagents on reaction vessels: Reaction vessels used in the manufacturing process may be metallic such as iron, cast iron, galvanized iron, copper, silver, aluminium, nickel, zinc and lead.

Atmospheric contamination during manufacturing process: Atmosphere may contain dust (sulphur, aluminum oxide, silica, soot etc.) and some gases like carbon dioxide, sulphur dioxide, arsine and hydrogen sulphide. These may contaminate the final product during the manufacturing process.

Chemical process used in the manufacture: Various chemical reactions such as oxidation, nitration, reduction, halogenations, hydrolysis are involved for the synthesis of drugs. In these chemical reactions various chemicals and tap water is used it is often having Mg+2, Ca+2 and Ch, which are generally found in the substance which is being manufactured.

Defects in the manufacturing process : Defects like incompleteness, pH, pressure, temperature and imperfect mixing in various manufacturing processes produce impurities in chemical compounds.

To prevent these impurities many test such as limit test are carried out to lower the impurities and to make the pharmaceuticals more safe.

Limit Test

Limit test is defined as quantitative or semiquantitative test designed to identify and control small quantity of impurity which is likely to be present in the substance.

Limit test is generally carried out to determine the inorganic impurities present in the compound.

Limit test for chlorides, sulphates, iron, lead and heavy metal are carried out in Nessler cylinders. Nesseler cylinders are made up of borosilicate glass that is colourless. It has the fixed diameter, length as per according to the Indian Pharmacopeia.

Two similar kind of cylinders are required each time i.e. one for the ‘Test’ sample and other for the ‘standard’ to make comparison in the identical manner. The quantities of the sample vary according to the , limits of impurities while the standard remains constant.

No numerical values for ths limits in these tests are prescribed in the pharmacopoeias, as it is not practicable. Generally an aqueous solution of the substance is prepared.

Sometimes a solution of the, substance is prepared by dissolving in an acid or if the solution is alkaline it is neutralized with nitric or hydrochloric acid as specific in the monograph of the pharmacopoeia. The Extent of opalescence, turbidity and colour is affected by other impurities present in the substance.

Limit Test for Chloride

Limit test of chloride is based upon the chemical reaction between silver nitrate and soluble chlorides in presence of dilute nitric acid to give opalescence (solid particles) of silver
chloride. Opalescence produced is compared with the standard solution. If the opalescence in the sample is less than the standard, it passes the test. If it is more than the standard, it fails the test.

Limit Test for Chloride

Procedure

Take two 50 ml Nessler Cylinders.-Label one as “Test” and- the other as ‘Standard’.

 

Limit Test for Chloride

Then observe both Nesseler cylinder from the side and from above against a black background and compare the turbidity. The turbidity developed in the test solution is not thicker than that of standard solution.

Limit Test for Iron

Limit test of iron is based on the reaction of iron with thioglycolic acid in the presence of citric acid and ammonia when pale pink to deep reddish purple colour is produced. Citric acid forms a complex with iron and prevent its precipitation by ammonia as ferric hydroxide. It will result to the formation of purple coloured ferrous salt of thioglycolic acid.

Limit Test for Iron

The colour produced is due to the formation of a ferrous compound with thioglycolic acid. It is stable in the presence of air but fades when exposed to air due to oxidation to the
ferric compound.

Standard Iron Solution: Accurately 0.1726g of ferric ammonium sulphate is weighed and dissolved in 10ml of 0.1N sulphuric acid and sufficient water to produce 100ml. Each ml of this solution contains 0.02mg of iron.

Procedure

Take two 50ml Nesseler cylinders. Label one as the ‘Test’ and the other as ‘Standard’.

Limit Test for iron

 

Compare the purple colour in two Nesseler cylinders by viewing vertically downwards. Any colour produced in test solution should not be more intense than the standard solution.

If the intensity of the colour is more in test than in the standard, it means that the sample contains more quantity of iron impurity than the permissible limit and hence the sample is
declared as not of standard quality

The colour in the test and the standard should be compared immediately after five minutes allowed for full development of the colour is over. If there is any delay, the colour
fades due to oxidation and the test becomes unreliable.

List of substances for which limit test of iron is prescribed in I.P. 1996.

  1.  Calcium carbonate
  2. Calcium chloride
  3. Zinc oxide
  4. Zinc sulphate
  5. Heavy magnesium carbonate
  6. Light magnesium carbonate
  7. Sodium acetate
  8. Sodium bicarbonate
  9. Sodium chloride

Limit Test for Sulphate

Limit test of sulphate is based on the reaction of soluble sulphate with barium chloride in presence of dilute hydrochloric acid to form barium sulphate which appears as solid particles (turbidity) in the solution.

Limit Test for Sulphate

Hydrochloric add is added to prevent precipitation of other acid radicals such as phosphate, oxalate etc. by common ion effect with barium chloride sol. So that less barium ions are formed.

Reagents:

Barium Sulphate Reagent: 15ml of a 0.5M barium chloride, 55ml of water and 20ml of sulphate-free alcohol are mixed, 5ml of a 0.0181% w/v solution of potassium sulphate are added, diluted to 100ml with water and mixed. Barium sulphate reagent must be freshly prepared.

0.5M Barium Chloride: Barium chloride dissolved in water to contain in 1000ml 122.1g ofBaClÿHjO.

Procedure: Take two 50ml Nesseler cylinders. Label one as “Test” and the other as “Standard”.

 

Limit Test for Sulphate

Stirr immediately each solution with a glass rod and allow to stand for 5 minutes, Compare the turbidity transversally against a black background in two Nesscler cylindres. Any colour
produced in test solution should not he more intense than the standard solution.

LimitTest for Heavy Metals

The limit test for heavy metals is based on the reaction between the solution of heavy metals and a saturated solution of Hydrogen sulphides. In acidic media, it produces reddish/black colour with hydrogen sulphide which is compared with standard lead nitrate solution.

LimitTest for Heavy Metals

It is designed to determine tire content of metallic impurities that are coloured by sulphide ion, under specified conditions. It is indicated in the individual monographs in terms of lead per million parts of tire substance (by weight), as determined by visual comparison of tire colour produced by the substance with that of a control prepared from a standard lead solution.

The amount of heavy metals is determined by one of tire following methods and as directed in the individual monographs. Method A is used for substances that yield clear, colourless
solutions under the specified test condition.

Method B is used for substances that do not yield dear, colourless solutions under tire test conditions specified for method A, or for substances which, by virtue of their complex nature, interfere with the precipitation of metals by sulphide ion. Method C is used for substances that yield clear, colourless solutions with sodium hydroxide solution.

Method A:

 

Method A

The colour produced in the test solution should not be darker than that produced in the standard solution.

Method B:

Method B

 

Method C:

 

Method C

The colour produced in the test solution should not be darker than the colour of the standard solution. Lead standard solution (20ppm Pb) is prepared by diluting 1 volume of lead standard solution (100 ppm Pb) to 5 volume with water.

Lead standard solution (100 ppm) itself is prepared by diluting 1 volume of lead standard solution (0.1% Pb) to 10 volume with water Lead standard solution (0.1% Pb) is prepared by dissolving 0.400 gm of lead nitrate in water containing 2 ml of cone. Nitric acid & adding sufficient water to produce 250 ml.

Limit Test for Lead

Lead is a toxic substance present in pharmaceutical preparations. The main source of this impurity are sulphuric acid and the lead apparatus. The I.P. and U.S.P. method is based on the reaction between lead and diathizone (diphenylthiocarbazone).

In chloroform solution dithizone extracts lead from an alkaline aqueous solution as lead dithizone which has red colour in chloroform solution. Since dithizone itself imparts a grÿn colour in chloroform, the resultant colour of dithizone and lead dithizone is violet.

The colour produced by a given amount of the sample is compared with that pro uce y a volume of a standard soluHon of lead. If the colour is intense than that produced by the standard, it contains lead in excess of the prescribed limit.

For the test, the lead present as impurity is separated by extracting an alkaline solution of the substance with dithizone extraction solution which removes all the lead in the form of its complex in chloroform layer.

Limit Test for Lead

Limit Test for Arsenic

The presence of arsenic in drugs even in the traces is not desirable because it is toxic and cumulative nature. The Indian Pharmacopeia prescribes the limits for the presence of arsenic
as an impurity in various drugs. For example:- Sodium chloride should not contain arsenic more than 1 parts per million.

Chemically, the arsenic impurity is converted in acidic medium into arsenious acid or. arsenic acid depending upon the valency state of arsenic:

Limit Test for Arsenic

The solution is then reacted with a reducing agent like stannous chloride or sulphurous acid to convert the pentavalent arsenic acid into the trivalent arsenious acid which is converted into gaseous arsenious hydride (arsine gas) with the help of nascent hydroeen produced by the acton of zinc with hydrochloric acid.

Limit Test for Arsenic 1

Arsine gas is carried out through the tube with the help of hydrogen to mercuric chloride paper. Reaction of arsine with mercuric chloride produces a yellow coloured stain. The intensity of the colour is dependent on the quantity of arsenic.

Limit Test for Arsenic 2

Method:

The volume of the prepared sample in a separator is transferred and unless otherwise directed in monograph, 6ml of ammonium citrate solution sp. and 2ml of hydroxylamine hydrochloride solution sp. are added (for the determination of lead in iron salts use 10ml of ammonium citrate solution sp.).

Two drops of phenol red solution are added and the solution made just alkaline (red in colour) by the addition of strong ammonia solution. The solution is cooled, if necessary and 2ml of potassium cyanide solution sp. are added.

Immediately the solution is extracted with several quantities, each of 5ml of dithiazone extraction solution, draining of each extract into another separating funnel, untill the dithiazone extraction solution retains its green colour.

The combined dithizone solutions are shaken for 30 seconds with 30ml of a 1% w/v solution of nitric acid and the chloroform layer discarded.

To the acid solution exactly 5ml of standard dithiazone solution and 4ml of ammonia cyanide solution sp. are added and shaken for 30 seconds, the color of the chloroform layer is of no deeper shade of violet than that of a control made with a volume of dilute standard lead solution equivalent to the amount of lead permitted in the sample under examination.

All reagents used for the test should have as low a content of lead as practicable. All reagent solutions should be stored in containers of borosilicate glass. Glassware should be rinsed throughly with warm dilute nitric acid, followed by water.

Apparatus:

The apparatus consists of a 100ml bottle or conical flask closed with a rubber or ground glass stopper through which passes a glass tube (about 20cm x 5mm). The lower part of the tube is drawn to an internal diameter of 1.0mm and 15mm from its tip is a lateral orifice 2 to 3mm in diameter.

When the tube is in position in the stopper in the lateral orifice should be at least 3mm below the lower surface of the stopper. The upper end of the tube has a perfectly flat surface atupper right angle to the axis of the tube.

A second glass tube of the same internal diameter and 30mm long, with a similar flat surface, is placed in contact with the first and is the lower tube insert 50 to 60mg of lead acetate cotton, loosely packed or a small plug of cotton and a rolled piece of lead acetate paper weighing 50 to 60mg.

Procedure for Limit Test for Arsenic

Between the flat surface of the tubes place a disc or a small square of mercuric chloride paper large enough to cover the orifice of the tube (15mm x 15mm). The purpose of lead acetate cotton is to trap any hydrogen sulphide (H2S) gas which would otherwise interfere with this test as it also give some stain with mercuric chloride paper.

The tube is fitted at its upper end with two rubber bungs as shown in figure. A piece of dry mercuricpaper is placed flat on the top of the bung and the other bung is place over it and secured by means of clips in such a manner that the borings of the two bung meet to form a true tube of the same diameter (6.5mm) interrupted by a diaphragm of mercuric chloride paper.

Separate apparatus is used for the test and the standard.

Notes:

  1. The test is a modification of the Gutzeit test and is, therefore called modified Gutzeit test.
  2. All the reagents which are used for this test should have a low content of arsenic as possible free from arsenic impurity.
  3. Potassium iodide is used because it helps in the reduction of pentavalent arsenic acid into trivalent arsenic acid.
  4. Granulated zinc is used instead of ordinary zinc because evolution of nascent hydrogen is steady and prolonged with granulated zinc.
  5. The arsenic impurity is expressed in terms of ppm (parts per million). One ppm is lmg in 1kg.

Limit test for Arsenic in Ammonium Chloride:

Limit testforArsenic in Ammonium Chloride

 

Place the prepared glass tube quickly in position in both the cases and allow the action to proceed for 40 minutes in the dark . compare the yellow stain in the two, in day light without delay.

After 40 minutes any stain produced on the mercuric chloride paper in test is not more intense than that obtained by the ‘Standard’.

Modified procedures for certain limits tests

1. Chloride and Sulphate in Potassium Permanganate

Principle : When limit test of chloride and sulphate are done in usually way, it will be very difficult to make any observation, since the sample itself (Potassium permanganate)
is highly coloured. So the presence of potassium permanganate can be reduced by alcohol. This process is known as PRETREATMENT.

The sample is dissolved in water and heated on a water bath. Alcohol is added. It is filtered to remove the precipitate manganese dioxide. The filterate is colourless & can be used for performing the limit test for chloride and sulphate in the usual way.

Procedure: Dissolve 1.5gm of the sample which is accurately weighed, in 50ml of distilled water. Heat the solution on a water bath and add gradually 6ml of ethanol 95%. Further cool it and dilute to 60ml with distilled water and filter. The filterate (Solution A) is colourless.

For Limit Test for Chlorides

Take 40 ml of solution A and do the limit test for chloride.

For Limit for Sulphate

Take 10 ml of solution A and do the limit test for sulphate.

2. Chloride and Suijp hate in Sodium Bicarbonate

Principle: In the limit test of chloride and sulphate in sodium bicarbonate, the pretreatment consists of neutralising the sodium bicarbonate with an app. Mineral acid and using the neutralised solution for the particular limit test. In the case of limit test for chloride, the sample is dissolved in distilled water & neutralised with nitric acid.

Chloride and Suijp hate in Sodium Bicarbonate

In the case of limit test for sulphate, the sample is suspended in distilled water and neutralised with HC1.

Chloride and Suijp hate in Sodium Bicarbonate 1

In both cases, the solution should be stirred well and the effervescence should be allowed to subside.

Procedure :

For Limit Test of Chloride

Weigh accurately 1.25gm of the sample and dissolve it in 15ml of distilled water. Add 2ml of cone. Nitric acid, then apply the limit test for chloride to this solution

For Limit Test of Sulphate

Weight accurately about lgm of the sample and suspend it in 10ml of distilled water. Neutralise the solution with cone. Hydrochloric acid adding it gradually till the effervescence ceases out. Dilute to 15 ml with distilled water. Do the limit test for sulphate with this solution.

Types Of Impurities In Pharmaceutical Substances Very short answer questions

Question 1. Why only distilled water or purified water is used in performing limit tests?
Answer. In performing limit tests only distilled water or purified water is used because ordinary tap water contains number of ions to validated the test.

Question 2. Why nitric acid is used in performing limit test for chloride?
Answer. Nitric acid is added to prevent precipitation of add radicals such as phosphate, sulphate etc. with silver nitrate because in the presence of nitric add other predpitates are not produced and only chlorides get predpitated.

Question 3. Why HC1 is used in the limit test of sulphate?
Answer. To remove the impurities ofsulphate.

Question 4. Why Barium chloride is used in the limit test of sulphate?
Answer. Barium chloride reacts with a sulphate to produce barium sulphate which can be seen as a white predpitable e.g. therefore can be identified.

Question 5. What is the reagent used in preparingbarium sulphate?
Answer. Sulf + Barium.

Question 6. What do you understand by the term ppm?
Answer. ppm is parts per million. One ppm is lmg in 1kg.

Question 7. Why granulated zinc is used instead of ordinary zinc?
Answer. Granulated zinc is used instead of ordinary zinc because evolution of nascent hydrogen is steady and prolonged with granulated zinc.

Question 8. What do you understand by the term limit tests?
Answer. Limit test is defined as quantitative or semi quantitative test designed to identify and control small quantity of impurity which is likely to be present in the substance.

Question 9. Is there any special apparatus or container required for carrying out limit test?
Answer. Yes Nessler cylinders are required for performing the limit test

Types Of Impurities In Pharmaceutical Substances Fill in the blanks

1. Limit test are qualitative e.g. ………………..test to identify and control small quantities of impurities.

Answer Quantitative

2. Limit test for chloride has been based upon reaction between……… and ……….to obtain silver chloride.

Answer AgN03/Soluble chloride

3. Limit test for sulphate has been based upon the ppt of sulphate with……… in presence of…….

Answer Barium chloride/Hydrochloride

4, Limit test for iron ferrous thioglycolate has stable pink to reddish purple colour in……… medium.

Answer Thioglycolic acid

5. Limit test of iron is based upon reaction of Fe with…………. ammonium citrate

Answer Ferrous mercaptoacetate

6. Limit test for iron purple colour is due to the formation of…….

Answer Alkaline

7. The limit test for arsenic is based upon……..

Answer Guizet test

8. The limit test for arsenic,……… is convertedinto arsenous acid/arsine gas.

Answer Arsine

9. The function of granulated zinc in limit test for arsenic is……

Answer Slow and prolonged evolution of nascent H2 gas.

10. In limit test for heavy metals…… is used for clear colorless/turbid colored solution.

Answer Method A

11. In limit test the change in……..is compared with fixed standard in the pharmacopeia.

Answer Colour, turbidity

12. If the test solution colour, turbidity or opalescence is less than that of the standard solution it……………….the limit test.

Answer Passes or fails

Major Extra And Intracellular Electrolytes

Major Extra And Intracellular Electrolytes Introduction

Electrolyte is a substance that ionizes when dissolved in a suitable ionizing solvents such as water. This includes most soluble acids, bases and gases. An electrolyte may be
defined as concentrated if it has high concentration of ions or dilute if it has low concentration of ions.

Electrolytes are used in replacement therapy and for the correction of acid-base balance in various body fluids. The electrolyte concentration of body fluids have been different in
various body fluid compartments. The various body fluid compartments are:-

1) Intracellular fluid:- This is the fluid which is present inside cell E.g. Cytoplasm. It constitutes 12-15% of body weight and its volume is 30 litres.

2) Extracellular fluid:- This is the fluid which is present between the cells E.g. Blood plasma. This constitutes 12-15 % of body weight and its volume is 10 litres.

3) Plasma (vascular) fluid:- This is the fluid which is present within the blood vascular system. This constitutes 4-5% of body weight and its volume is 3-5 litres.

The major electrolytes found in the body are:- Calicum, Potassium, Phosphate, Iron, Magnesium, Chloride, Sodium.

Read and Learn More Pharmaceutical Inorganic Chemistry Notes

Major Physiological Ions

Calicum:- Calicum is an important constitutent of bones and teeth. It is also concerned with the functioning of muscles and clotting mechanism of blood .The main sources of Cal
cium include milk, cheese, green vegetables, egg and fish.

Magnesium:- The total magnesium content in body is about 25 gram of magnesium and the daily requirement is 350 mg. The main sources of magnesium include nuts, soyabeans, wholegrains, seafoods.

It is used for protein synthesis and for the smooth functioning of the neuromuscular system. Its deficiency cause personality changes, loss in body weight and cardiac disturbances. It is the second most cation in concentration in the intracellular fluid compartment.

Chloride:- It is the major extracellular anion. The total chloride ion present in the body is about 50mEq per body weight and body daily requirement is about 5-10 gm as sodium chloride.

The main source of chloride required for the body is table salt which is used in cooking. Chloride ion is excreted through the urine and through the skin during sweating. It is required for maintaining proper hydration, osmotic pressure and normal cation-anion balance.

Potassium:- It is the major intracellular cation present as about 23 times higher than present in the extracellular fluid in the human body. Human body has about 2.6 per kg weight of potassium.

The main source of potassium in food includes milk, certain vegetables, meat and whole grains. Potassium ions are used to maintain the electrolyte composition of various body fluids, help to regulate pH by exchange against for hydrogen ions and in many biochemical activities inside the cell.

Sodium:- It is the most abundant extracellular ion. It constitutes nearly 90% of extracellular cations. The normal sodium content in the body varies from 5to 20 gm and the daily
requirement is in between 3-5 gm.

The main source of sodium required for our body is tablesalt which is used in cooking. Sodium plays an important role in the maintence of osmotic pressure of various body fluids and in the transmission of nerve impulses in the nerve fibre.

Phosphate:- It is the principal anion of the intracellular fluid compartment. The main sources of phosphate are cereals, pulses, nuts and oil-seeds. It is an important buffer system and is also present in the bones.

Iron:- It forms an important component of haemoglobin which acts as a carrier of oxygen in the blood. The main sources of iron include green leafy vegetables, millets like bajra
and ragi. It is necessary for growing children and pregnant women. The deficiency of causes anaemia and goitre.

Electrolyte Distribution

 

ELECTROLYTE DISTRIBUTION

Electrolyte Used In Replacement Therapy

In normal conditions, the body is able to adjust the electrolyte balance while in some conditions such as prolonged fever, severe vomiting or diarrohea, there occurs a heavy loss
of water and electrolyte. So, there is need to administration of lost electrolyte.

There some electrolytes that are used in replacement therapy are sodium chloride and its salts such as sodium chloride injection, hypertonic solution, sodium lactate injection, potassium chloride and its salts.

Sodium Chloride

Chemical formtila:-NaCl                   Molecular weight;- 58.45

In the nature, it is found in sea water, in seawells, lakes(sambhar in India)and in deposits of rock salts.

Preparation

In the laboratory, it is prepared from common salt(impure) in water by passing hydrochloric acid gas. The crystals are precipitated out. Industrially, it is prepared by evaporation of sea-water in shallow pans.

It contain certain impurities which are removed by dissolving common salt in water in cemented tanks. Some alum and lime are added. The suspended impurities get settle down easily.

Physical Properties

Sodium chloride occurs in the form of colourless, transparent cubes or as a white, crystalline powder.
It is colourless
It has a saline taste
It is slightly hygroscopic

Chemical Properties
1 . Sodium chloride is rather easily oxidised to liberate free chlorine. For e.g. heating with manganese dioxide & cone, sulphuric aied produces chlorine.

Chemical Properties Of Sodium Chloride

2. Sodium chloride when react with silver nitrate gives a curdy precipitate of silver chloride.

Chemical Properties Of Sodium Chloride 1

The precipitate which is affected by light is soluble in dilute ammonia and insoluble in nitric acid.

Uses

It is used as an electrolyte replenishes emetic. Jt can be used in homeopathetic medicine.  Solution of sodium chloride may be used as an eye-drop, nasal drop( to relieve nasal congestion) and as a mouthwash (to remove debris).

Assay

An accurately weighed quantity is dissolved in water & a known excess of 0.1M AgNO solution, dil. HNO and diethyl phthalate are added. It is titrated with 0.1M ammonium
thiocynate solution using ferric ammonium sulphate as indicator.

This is a modified Volhard’s method. Sodium chloride is precipitated as silver chloride by the addition of silver nitrate. Dibutyl phthalate is added to coat the silver chloride so that it will not interfere with the titration off the excess of AgN03 with 0.1M ammonium thiocyanate, since silver chloride reads slowly with ammonium thiocyanate.

Previously (in I.P. 66) sodium chloride was assayed by direct titration in neutral solution with 0.1N silver nitrate using potassium chomate as indicator.

Dibutylphthalate

The same cannot be used now since silver chromate formed at the end point is soluble in acid.

Potassium Chloride

Chemical formula:-KCl

Molecular weight:-74.55

In nature it is found as syline (KCl) and camallite contaminated

KCl.MgCL2.6H2O with magnesium sulphate and chloride.

Preparation

Potassium chloride can be prepared by reacting hydrochloric acid with potassium carbonate.

POTASSIUM CHLORIDE

Properties

It occurs as colourless, odourless, cubical and crystalline powder. It is having saline taste. It is soluble in water, glycerol, practically insoluble in alcohol, solvent and ether. It diminish its
solubility in water.

Assay

The assay is based on Mohr’s method of direct volumetric precipitation titration. An aqueous solution of the solution is titrated against a standard solution of silver nitrate using
solution of potassium chromate as indicator.

Mohr's method

When whole of NaCl has been precipitated as AgCl, addition of silver nitrate solution gives a brick red colour with the indicator. The end point is change of colour from yellow to red.

Mohr's method

An aqueous solution of the weighed substance is titrated with 0.1N AgN03, using K2Cr2O7. solution as indicator. Each ml of 0.1N silver nitrate is equivalent to 0.007455g of KCl.

Uses:

It is used in the treatment of potassium deficiency. It is also used in the treatment of Myasthenia gravis( muscle weakness) and as an antidote for digitalis intoxication. It is used as an
electrolyte replenishes

Calcium Gluconate

CALCIUM GLUCONATE

Method of Preparation

It is prepared by boiling a solution of gluconic acid with excess of calcium carbonate, filtering and crystallising the substance from filtrate.

Method of Preparation

Properties

It occurs as odourless, white crystalline powder, tasteless, freely soluble in boiling water, sparingly soluble in water and insoluble in alcohol, ether and chloroform.

Uses: it is Used as a source of calcium ion in the treatment of calcium deficiency and hypocalcaemic tetany.

Assay

The assay is based on complexometric type titration forming a well defined simple complex between calcium and disodium ethylenediamine titracetate (EDTA) using mordant black II
as an indicator. The end point is a change of colour from red to blue. In this assay, a solution of magnesium sulphate is added before the titration to make the end point sharp.

Magnesium also forms a similar complex with EDTA. But these titration have to be carried out in the presence of buffer such as strong ammonia-ammonium chloride solution.

EDTA

An aqueous solution of the substane containing magnesium sulphate and strong ammoniaammonium chloride is titrated with 0.05M disodium ethylenediamine tetraacetate, using
mordant black II as indicator.

From the volume of 0.05M magnesium sulphate is substracted. Each ml o the remainder is equivalent to 0.024420g of CaC12H22O14.H2O.

Official Test for Identity

  1. Give the reactions characteristic of calcium.
  2. To a solution of the substance in water, ferric chloride solution is added. A yellow colour is produced.

Oral Rehydration Salt (Ors)

Oral rehydration salt contain anhydrous glucose, sodium chloride, potassium chloride and either sodium bicarbonate or sodium citrate. These dry preparations are to be rrux HI specific amounts of water along with certain flavouring agents and a suitable agents or ee flow of powder.

These are used for oral rehydration therapy. In ancient times, homema e ORS is used which constitutes of one tablespoonful of salt, two tablespoonfuls of sugar in litre of water.

The following three formulations are usually prepared. When glucose is used, sodium bicarbonate is packed separately. The quantities given below are preparing 1 litre solution.

The Oral Rehydration Therapy (O.R.T.) has several advantages :

  1. Patients strong enough to drink take this easily.
  2. Vomiting is easily corrected by the therapy itself.
  3. Solution should be sterile.
  4. This oral treatment is very cheap.
  5. It can be given by intravenous mode also.
  6. It is given easily by the mouth.

 

ORAL REHYDRATION SALT (ORS)

The power may be dissolved in boiled water and made up to one litre. It contains the same proportions of electrolyte as in the previous formula except that this powder contains
9.9 mEq/1 of citrate in place of the bicarbonate.

The formulae II and III are recommended by WHO And UNICEF for control in diarrhoeal diseases.

New Formula Oral Rehydration Salts By Who

A new formula for oral rehydration salts (ORS), has been released by the World Health Organization (WHO). The new formula ORS, a sodium and glucose solution, is widely used
to treat children with acute diarrhea.

Since WHO adopted ORS in 1978 as its primary tool to fight diarrhea, the mortality rate for children suffering from acute diarrhea has fallen from
5 million to 1.3 million deaths annually.

The new improved formula fe the result of extensive research sponsored by WHO’s Department of child and adolenscent Health and development and suppoerted by the united states agency for International Development (USAID).

 

NEW FORMULA ORAL REHYDRATION SALTS BY WHO

Physiological Acid-Base Balance

Body fluids are having balanced quantity of acids and bases and this quantity is maintained by intricate mechanism. The maintenance of this balance quantity is necessary for biochemical reaction talking places in body, because biochemical reaction are very sensitive to even small change of acids and bases.

Example: LOW pH value in stomach is requiring for functioning of enzyme pepsin which is useful for digestion of food.

The pH values of certain body fluids are:

 

PHYSIOLOGICAL ACID-BASE BALANCE

Body is having its own buffer system which prevents little change in the pH value of blood. It also helps to convert strong acids and bases into weak acids or bases. Lungs and kidney the main organ which helps to maintain buffer system in the body.

In case of low respiration, the accumulated carbon dioxide combines with water and forms carbonic acid which releases hydrogen ions and causes respiratory acidosis.

PHYSIOLOGICAL ACID-BASE BALANCE

In over-breathing, excessive excretion of carbon dioxide occurs and causes respiratory alkalosis.

Kidney has ability to generate ammonia which neutralizes acid products of protein metabolism and excrete in urine

Conditions where metabolic alkalosis occurs:

  1. Loss of chloride ions
  2. Administration of diuretics
  3. Excessive ingestion of alkaline drugs
  4. Endocrine disorder

Conditions where metabolic acidosis occurs:

  1. Absorption of excess metabolic acids
  2. Formation of excessive quantities of metabolic acids like carbonic acids
  3. Failure to excrete metabolic acids
  4. Loss of base from body fluids
  5. Diabetes mellitus
  6. Diarrhoea
  7. Uremia
  8. Excess vomiting

Major Extra And Intracellular Electrolytes Very Short Questions and Answers

Question 1. Name the major ions involved in the fluid and electrolyte balance and briefly describe their major location.
Answer.

  1. Sodium is the most abundant extracellular ion and represents about 90 percent of extracellular cations.
  2. Potassium is the most abundant cation in the intracellular fluid.
  3. Calcium is the most abundant ion in the body and is principally an extracellular extracellular electrolyte.
  4. Magnesium is primarily an intracellular electrolyte.
  5. Chloride is the major extracellular anion.
  6. Phosphate is principally an intracellular electrolyte.

Question 2. Name the substances that dissociate in Water and form ions?
Answer. Electrolytes.

Question 3. Name the largest body fluid Compartment?
Answer. Intracellular compartment.

Question 4. What is ORS?
Answer. Oral rehydration salt.

Major Extra And Intracellular Electrolytes Multiple Choice Question And Answers

Question 1. The body fluids found within the cells is called

  1. plasma.
  2. extracellular fluid.
  3. interstitial fluid.
  4. intracellular fluid.
  5. water.

Answer: intracellular fluid.

Question 2. Blood plasma belongs to

  1. intracellular fluid.
  2. extracellular fluid.
  3. interstitial fluid.
  4. Both B and C.
  5. None of the above.

Answer: interstitial fluid.

Question 3. Most solutes in body fluid are,

  1. electrolytes.
  2. proteins.
  3. sugars.
  4. amino acids.
  5. lipids.

Answer: electrolytes.

Question 4. Water lost through the actions of the

  1. kidneys.
  2. gastrointestinal tract.
  3. lungs.
  4. skin.
  5. All of the above.

Answer: All of the above.

Question 5. Total fluid output of the body under normal conditions is approximately

  1. 200 ml/day.
  2. 2500 ml/day.
  3. 400 ml/day.
  4. 1500 ml/day.
  5. 4300 ml/day.

Answer: 2500 ml/day.

Question 6. Which of the following ions diffuses easily between extracellular and intracellular compartments?

  1. magnesium
  2. chlorine
  3. sodium
  4. phosphate
  5. potassium

Answer : chlorine

Question 7. The major route of excretion for sodium ions (under normal conditions) is the

  1. skin.
  2. kidney.
  3. GI tract
  4. adrenal cortex.
  5. sweat

Answer : kidney.

Question 8. KC1 is indicated in the treatment of………

  1. menieres syndrome
  2. antidote in digitalis intoxication
  3. myasthenia gravis
  4. all of the above.

Answer: myasthenia gravis

Question 9. Calicum is essential for…………

  1. blood pontification to whaler bone
  2. blood clotting
  3. Myasthenia gravis
  4. All of the above

Answer: blood clotting

Question 10. The principal function of chloride is………

  1. Maintenance of proper hydration.
  2. Maintenance of osmotic pressure.
  3. Normal Electrolytic balance
  4. All of the above

Answer: All of the above

Major Extra And Intracellular Electrolytes Fill In The Blanks

1. Sodium chloride is used as………

Answer. Fluid and electrolyte replenisher

2. …….and…….. are found in plasma and interstitial fluid.

Answer. Na, Cl

3. ……..are found in intracellular fluid.

Answer. K, Mg,P04

4. The basic objective of replacement therapy is….

Answer. to restore the volume and composition of body fluids.

5. Replacement therapy is needed for…………..

Answer.Heavy loss of water,diarrhoea, prolonged fever

6. Electrolytic solution can be given by………..and………….

Answer.Oral, i.v.

7. ORS stands for………..

Answer. Oral rehydration salt

8. Homemade ORS constitutes of ……………

Answer. One half tablespoonful of salt, two tablespoonful of sugar in 1 litre of water

9. The concentration of electrolytes is expressed in,………….

Answer.Milliequivalents per litre

10. Extracellular fluid includes………………..

Answer. Intestinal and vascular fluid.