Sainavle

• Chapter 1 Crop Production and Management Notes
• Chapter 2 Microorganisms: Friend and Foe Notes
• Chapter 3 Coal and Petroleum Notes
• Chapter 4: Combustion and Flame Notes
• Chapter 5: Conservation of Plants and Animals Notes
• Chapter 6 Reproduction in Animals Notes
• Chapter 7: Reaching the Age of Adolescence Notes
• Chapter 8 Force and Pressure Notes
• Chapter 9 Friction Notes
• Chapter 10 Sound Notes
• Chapter 11 Chemical Effects of Electric Current Notes
• Chapter 12: Some Natural Phenomena Notes
• Chapter 13 Light Notes

CBSE Class 10 Science Short Answer Questions

• Chapter 1 Chemical Reactions And Equations
• Chapter 2 Acids, Bases And Salts
• Chapter 3 Metals And Non-Metals
• Chapter 4 Carbon And Its Compounds
• Chapter 5 Periodic Classification Of Elements
• Chapter 6 Life Processes
• Chapter 7 Control and Coordination
• Chapter 8 How do Organisms Reproduce

• Chapter 9 Heredity And Evolution
• Chapter 10 Light-Reflection 10 And Refraction
• Chapter 11 Human Eye And Colourful World
• Chapter 12 Electricity
• Chapter 13 Magnetic Effects Of Electric Current
• Chapter 14 Sources Of Energy
• Chapter 15 Our Environment
• Chapter 16 Management Of Natural Resources

CBSE Class 10 Science Chapter 1 Chemical Reactions And Equations Very Short Question And Answers

Question 1. Out of rusting of iron or melting of iron, which one is a physical change?
Answer: Melting of iron

Question 2. In the electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?
Answer:

Because during electrolysis, water splits into two molecules of hydrogen and one molecule of oxygen.

2HO  → (Electrolysis )  → 2 H₂O

Question 3. Which one is a chemical change, electrolysis of water or Sodium chloride exposed to sunlight?
Answer: Electrolysis of water

Question 4. All decomposition reactions are endothermic reactions. Explain why?
Answer: Because energy in the form of heat, light or electricity is required for decomposition.

Question 5. What change in colour is observed when white silver chloride is left exposed to sunlight? State the type of chemical reaction in this change.
Answer:  Silver chloride becomes grey. It is a photochemical decomposition reaction.

Question 6. Balance the given chemical equation:

⇒ \(\mathrm{Fe}(\mathrm{s})+\mathrm{H}_2 \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{Fe}_3 \mathrm{O}_4(\mathrm{~s})+\mathrm{H}_2(\mathrm{~g})\)

Read and Learn More CBSE Class 10 Science Very Short Answer Questions

Answer:

⇒ \(3 \mathrm{Fe}(\mathrm{s})+4 \mathrm{H}_2 \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{Fe}_3 \mathrm{O}_4(\mathrm{~s})+4 \mathrm{H}_2(\mathrm{~g})\)

Question 7. Balance the given chemical equation:
Answer: FeSO₄(s)   → (Heat) → Fe₂O₃(s) + SO₂(g) + SO₃(g)

Question 8. Balance the following chemical equation:

⇒ \(\mathrm{Fe}(s)+\mathrm{H}_2 \mathrm{O}(g) \longrightarrow \mathrm{Fe}_3 \mathrm{O}_4(s)+\mathrm{H}_2(g)\)

Answer:

⇒  \(3 \mathrm{Fe}(s)+4 \mathrm{H}_2 \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{Fe}_3 \mathrm{O}_4(\mathrm{~s})+4 \mathrm{H}_2(g)\)

Question 9. What type of coating is formed on silver articles when they get corroded?
Answer: The silver articles form a black coating of silver sulphide (Ag₂S).

Question 10. On what basis is a chemical equation balanced?
Answer: It is based on the law of conservation of mass.

Question 11. Balance the given chemical equation:

Al(s) + CuCl₂(aq)→  AlCl₃(aq) + Cu(s)

Answer: 2Al(s) + 3CuCl₂(aq)→ 2AlCl₃(aq) + 3Cu(s)

Question 12. What type of coating is formed on copper articles when they get corroded?
Answer: The copper articles form a green coating of basic copper carbonate

Question 13. State one basic difference between a physical change and a chemical change.
Answer:

In a physical change, no new substance is formed whereas in a chemical change, a new substance is formed.

Question 14. On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue-green. Predict the new compound formed which imparts a blue-green colour to the solution.
Answer:

The new compound formed is copper (II) chloride (CuCl2) which imparts a blue-green colour to the solution.

Question 15. Name the oxidising and reducing agent in the following reaction: Cu + H₂O→Cu + H₂O
Answer:

The oxidising agent is CuO.

The reducing agent is H₂.

Question 16. What is meant by the skeletal equation?
Answer: An unbalanced chemical equation is called a skeletal equation.

Question 17. If copper metal is heated over a flame, it develops a coating. What is the colour and composition of this coating?
Answer: The colour of the coating is black and it is composed of CuO or copper oxide.

Question 18. Which one is a chemical change – Electrolysis of water or sodium chloride exposed to sunlight?
Answer: Electrolysis of water

Question 19. A magnesium ribbon should be cleaned before burning it in the air. Why?
Answer: It should be cleaned to remove the dust particles and the oxide that may be present on its upper surface so that it comes directly in contact with air.

Question 20. Which of the following is a chemical change?

1. Burning of wax
2. Melting of wax

Answer: 1. Burning of wax

Question 21. Why do gold and platinum not corrode in moist air?
Answer: They are least reactive and do not react with substances present in moist air.

Question 22. Why do potato chip manufacturers fill the packet of chips with nitrogen gas?
Answer: To provide an inert atmosphere to prevent chips from getting oxidised. N₂ does not allow chips to get spoiled by oxidation.

Question 23. How will you define a reducing agent?
Answer: A reducing agent is a substance which can lose electrons or which can add hydrogen or remove oxygen.

Question 25. Name the process in which the gain of electrons takes place.
Answer: Reduction is a process which involves the gain of electrons

Question 24. A white salt on heating decomposes to give brown fumes, and a residue is left behind. Name the salt.
Answer: Lead nitrate is white salt.

Question 25. Hydrogen is a highly inflammable gas and oxygen is a supporter of combustion, yet water which is a compound made up of hydrogen and oxygen is used to extinguish fire. Why?
Answer:

This is because the properties of the compound (H₂O) are different from the properties of its constituting elements, i.e., H₂ and O₂.

Question 26.

• AgNO₃(aq) + NaCl(aq)→ AgCl(s) ↓ + NaNO₃(aq)
• FeS + H₂SO₄ →FeSO₄ + H₂S ↑

Consider the above-mentioned two chemical equations with two different kinds of arrows(↑ and ↓) along with products. What do these two different arrows indicate?
Answer:

↑ shows the gas evolved, whereas shows an insoluble substance (precipitate) formed.

Question 27. What is the colour of FeSO₄.7H₂O crystals? How does the colour change upon heating? Give a balanced chemical equation for the change. 
Answer:

FeSO₄. 7H₂O is green and loses water of crystallisation when it is heated. It is then decomposed to Fe₂O₃ (brown-coloured), SO₂ and SO₃

2FeSO₄(s) → Fe₂O₃(s)+  SO₂(g) + SO₃(g)

Question 28. Oil and fat-containing food items are flushed with nitrogen. Why?
Answer: To keep food items fresh and to save from the oxidising effect of oxygen, food items are flushed with nitrogen gas.

Question 29. Why do we store silver chloride in dark-coloured bottles?
Answer: Because silver chloride on exposure to sunlight undergoes dissociation.

Question 30. A boy has been collecting silver coins and copper coins. One day he observed a black coating on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for these coatings?
Answer: The phenomenon responsible for these coatings is corrosion.

Question 31. FeSO₄. 7H₂O, green colour crystals on heating changes colour. Why?
Answer:  The green colour of ferrous sulphate crystals is due to the presence of 7 water molecules (water of crystallisation).

CBSE Class 10 Science Light-Reflection And Refraction Very Short Questions and Answers

Question 1. Define the term reflection.
Answer: The bouncing back of light when it strikes a polished surface is called the reflection of light.

Question 2. State the laws of reflection.
Answer:

1. The angle of incidence is equal to the angle of reflection i.e. Li = r.
2. The incident ray, the normal and the reflected ray, all lie in the same plane.

Question 3. What is the radius of curvature of a plane mirror?
Answer: Infinity

Question 4. How will you identify a convex lens by touching it?
Answer: A convex lens is thinner at the center and thicker at the edges.

Question 5. What is the velocity of light in a glass slab with a refractive index of 1.5?
Answer:

v\(=\frac{c}{\mu}=\frac{3 \times 10^8}{1.5}=\)2 × 10⁸ m/s.

Read and Learn More CBSE Class 10 Science Very Short Answer Questions

Question 6. The refractive index of a diamond is 2.42. What is the meaning of this statement about the speed of light?
Answer: It means that light travels 2.42 times faster in a vacuum than in a diamond.

Question 7. For the same angle of incidence, the angle of refraction in three media A, B, and C are 15°, 25°, and 35° respectively. In which medium is the velocity of light minimum?
Answer: In medium C.

Question 8. What will be the focal length of a lens whose power is given as +2.0 D?
Answer:

Given

f = ?, P = + 2.0 D

P = \(\frac{1}{f}\)

⇒ \(\frac{1}{\mathrm{P}}=\frac{1}{2}=0.5 \mathrm{~m}\)

Question 9. Define the term power of a lens.
Answer: It is defined as the ability of a lens to converge or diverge a beam of light falling on it.

Question10. What does positive magnification imply?
Answer: It means that the image formed is erect and virtual.

Question 11. An incident ray falls normally on a glass slab, what is the angle of refraction?
Answer: Zero

Question 12. What type of lens behavior will an air bubble inside water show?
Answer: It will act as a concave lens.

Question 13. What is the expression for the magnification of a lens?
Answer:

⇒ \(m=\frac{-v}{u}\)

Question 14. A thin lens has a focal length of -12 cm. Is it a convex lens or a concave lens?
Answer: Concave lens

Question 15. When the light of 2 colors, A and B is passed through a plane boundary, A is bent more than B. Whcolorlour travels more slowly in the second medium.
Answer: Colour A travels slowly.

Question 16. Between which 2 points related to a concave mirror should an object be placed to obtain on a screen an image twice the size of the object?
Answer: Real image – Between F and C.

Question 17. The speed of light in a transparent medium is 0.6 times that of its speed in a vacuum. What is the refractive index of the medium?
Answer:

⇒ \(n=\frac{c}{v}\)

⇒ \(n=\frac{c}{0.6 c}=\frac{1}{0.6}=1.66\)

Question 18. A person wants a full-length image of a tall building in a small mirror. What type of mirror is used by him?
Answer: Convex mirror

Question 19. Does the value of the speed of light change with the medium?
Answer: Yes, in a denser medium, it becomes less than that in free space.

Question 20. When the angle of incidence is 90°, what is the angle of refraction?
Answer:

n = \(\frac{\sin i}{\sin r}\)

For i = 90°

r = \(\sin ^{-1}\left(\frac{1}{n}\right)\)

Question 21. How does the frequency of a beam of ultraviolet light change when it goes from air into glass?
Answer: Frequency remains the ins same on change of medium.

Question 22. What is the unit of power of a lens?
Answer: Dioptre

Question 23. Give two uses of a convex lens.
Answer:

1. Used in camera.
2. Used in projectors.

Question 24. Mention two properties the the of image formed by a convex mirror.
AnswThe image

1. mage produced is virtuTheimagee mage produced is erect.

Question 25. A lens X has a focal length of 20 cm and a lens Y has a focal length of 40 cm. Which lens would you select to obtain a more convergent beam of light?
Answer: The lens has an ing focal length of 20 cm as it will have more power.

Question 26. the the Can refractive index of a medium be less than unity? What is the value of the refractive index of a vacuum?
Answer: No, because the use speed of light a  in vacuum is maximThe refractivetive index for a vacuum is 1.

Question 27. An object is placed at a distance ‘u’ from the lens of focal length ‘The image is formed at a distance ‘v’ from the lens. Write the relation between u, and v, f.
Answer:

⇒ \(\frac{1}{f}=\frac{1}{v}=\frac{1}{u}\)

Question 28. What is the value of the speed of light in free space?
Answer: L = 3 × 10⁸ m/s

Question 29. Does the refractive index vary with the color of light?
Answer: Yes, (n_v>n_r).

Question 30. What is the importance of the optical center of a lens?
Answer: It signifies the point through which if a light goes, there will not be any direction.

CBSE Class 10 Science Chapter 6 Life Processes Very Short Answer Questions

Question 1. In the experiment “Light is essential for photosynthesis”, why does the uncovered part of the leaf turn blue-black after putting iodine solution?
Answer: Starch is produced in the uncovered part of the leaf which turns blue-black in the presence of iodine solution.

Question 2. State the basic difference between the process of respiration and photosynthesis.
Answer: Respiration uses O₂ and releases CO₂ but in photosynthesis, CO₂ is used and O₂ is released.

Question 3. Which pancreatic enzyme is effective in digesting proteins?
Answer: Trypsin is the pancreatic enzyme that is effective in digesting proteins.

Question 4. Why does lack of oxygen in muscles often lead to cramps among cricketers?
Answer: This is due to the conversion of pyruvate to lactic acid in the absence of oxygen.

Read and Learn More CBSE Class 10 Science Very Short Answer Questions

Question 5. What is peristaltic movement?
Answer: The contraction and expansion movement of the walls of food-pipe is called peristaltic movement. This pushes the food in a forward direction in the alimentary canal.

Question 6. Why is anaerobic respiration less efficient?
Answer: Anaerobic respiration is the incomplete breakdown of glucose and produces less energy, so it is less efficient.

Question 7. Why do mammals require a more extensive respiratory surface?
Answer: Mammals need more oxygen to meet the requirements of their high metabolic rate. Therefore they need extensive respiratory surface.

Question 8. How many chambers are present in the heart of fishes? How many times does blood flow through the heart during each cycle?
Answer: Two chambers are present in the heart of fishes. Blood flows one time through the heart during each cycle.

Question 9. What is the main function of Adam’s Apple?
Answer: The main function of Adam’s Apple is to produce voice in the presence of air.

Question 10. When we breathe out, why does the air passage not collapse?
Answer: The air passage does not collapse because it is supported by cartilaginous rings which prevent its collapsing.

Question 11. Mention the raw materials required for photosynthesis.
Answer: The raw materials required for photosynthesis are carbon dioxide and water in the presence of sunlight and chlorophyll.

Question 12. Mention the purpose of making urine.
Answer: The purpose of making urine is to filter out waste products (urea or uric acid) from the blood.

Question 13. In which part of the digestive system is water absorbed?
Answer: In the large intestine.

Question 14. Which type of nutrition is present in tapeworms?
Answer: Heterotrophic nutrition.

Question 15. Where does the digestion of fat take place in our body?
Answer: In the small intestine by the use of bile and lipase.

Question 16. What is the function of platelet cells in blood?
Answer: The platelet cells in blood circulate the body and help to clot the blood at the point of injury.

Question 17. The volume of glomerular filtrate produced is 18 L but the volume of urine excreted is just 1-2 L. Give a suitable reason for this statement.
Answer: It is because the remaining filtrate is reabsorbed in the kidney tubules.

Question 18. Name any two substances which are selectively reabsorbed from the tubules of a nephron.
Answer: Water, glucose, amino acid.

Question 19. How does the transportation of water occur at night in the absence of transpiration?
Answer: At night, the transportation of water occurs due to the root pressure.

Question 20. Why is the rate of breathing in aquatic organisms much faster than that in terrestrial organisms?
Answer: Because the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air.

Question 21. What role does bile play in digestion?
Answer: Emulsification of fats.

Question 22. Why do ventricles have thicker walls than auricles?
Answer: Some ventricles have to pump blood into various organs, therefore they have thicker muscular walls than the auricles.

Question 23. Name the component of food that is not digested in the stomach.
Answer: Roughage.

Question 24. During the breathing cycle, what is the advantage of residual volume of air in the lungs? Explain.
Answer: The advantage of residual volume of air in the lungs is that there is sufficient time for oxygen to be absorbed and for CO₂ to be released.

Question 25. Why do the walls of the trachea not collapse when there is less air in it?
Answer: The presence of rings of cartilage in the throat ensures that the air passage does not collapse.

Question 26. Name the component of blood that helps in the formation of blood clots in the event of a cut.
Answer: Platelet.

Question 27. What is ‘translocation’ in plants?
Answer: The transport of soluble products of photosynthesis is known as translocation.

Question 28. Name the intermediate and the end products of glucose breakdown in aerobic respiration.
Answer:

Question 29. Mention how organisms like bread molds and mushrooms obtain their food.
Answer: Organisms like bread molds and mushrooms break down the food materials outside the body and then absorb it.