CBSE Class 11 Chemistry P Block Elements Multiple Choice Questions

Question 1. The number of isomers possible for disubstituted borazine, B₃N₃H₄X₂ is-

1. 3
2. 4
3. 5
4. 6

Answer: 2. 4

Question 2. Pentaborane-9 (B₅H₉) is an example of—

1. Arachno-borane
2. Pseudo-borane
3. Nido-borane
4. Closo-borane

Answer: 1. Arachno-borane

Question 3. Si when reacts with A forms B. A & B respectively are

1. HF, H₂SiF₄
2. HF, H₂SiF₆
3. HCl, H₂SiCl₆
4. HI, H₂SiI₆

Answer: 2. HF, H₂SiF₆

Question 4. Boric acid is a

1. Monobasic and weak Lewis acid
2. Monobasic and weak Bronsted acid
3. Monobasic and strong Lewis acid
4. Tribasic and weak Bronsted acid

Answer: 1. Monobasic and weak Lewis acid

Question 5. Which ofthe following does not exist in a free state

1. BF₃
2. BCl₃
3. BBr₃
4. BH₃

Answer: 4. BH₃

Question 6. The correct order of decreasing Lewis acid character is

1. BCl₃ > AlCl₃ > GaCl₃ > InCl₃
2. AlCl₃ > BCl₃ > InCl₃ > GaCl₃
3. AlCl₃ > GaCl₃ > BCl₃ > InCl₃
4. InCl₃ > GaCl₃ > AlCl₃ > BCl₃

Answer: 1. BCl₃ > AlCl₃ > GaCl₃ > InCl₃

Question 7. Which of the following is present in the chain structure of silicate

1. (Si₃O^2-₅)_n
2. (Si₃O^2-₃)_n
3. (SiO^4-₄)
4. Si₂O^6-₇

Answer: 2. (Si₃O^2-₃)_n

Question 8. A metal, M forms chlorides in +2 and +4 oxidation states. Which ofthe following statements about these chlorides is correct

1. MCl₂ is more volatile than MCl₄
2. Ml₂ is more ionic than MCl₄
3. MCl₂ is more soluble in any. ethanol than MCl₄
4. MCl₂ is more easily hydrolysed than MCl₄

Answer: 2. Ml₂ is more ionic than MCl₄

Question 9. The number of O-atoms that are shared per Si04 tetrahedra in silicate anion of beryl is

1. 4
2. 3
3. 2
4. 1

Answer: 3. 2

Question 10. Which of the following on hydrolysis produces crosslinked silicone polymer

1. R₄Si
2. RSiCl₃
3. R₂SiCl₂
4. R₃SiCl

Answer: 2. RSiCl₃

Question 11. The antidote of poisoning caused by CO is

1. Carborundum
2. Carbogen
3. Carbonic acid
4. Pure oxygen

Answer: 2. Carbogen

Question 12. Carbon suboxide in reaction with water produces

1. Oxalic acid
2. Formic acid
3. Lactic acid
4. Malonic acid

Answer: 4.  Malonic acid

Question 13. The volume of which liquid metal increases on solidification

1. Ga
2. Al
3. Zn
4. Cu

Answer: 1. Ga

Question 14. Which ofthe following reacts only with alkali

1. B₂O₃
2. Al₂O₃
3. Ga₂O₃
4. ln₂O₃

Answer: 1. B₂O₃

Question 15. Which is the strongest Lewis acid

1. BF₃
2. BCl₃
3. BBr₃
4. BI₃

Answer: 4. BI₃

Question 16. The atomic radius of Ga is slightly less than that of Al. The reason is

1. Weaker shielding effect of -electrons of Ga
2. Stronger shielding effect of s -electrons of Ga
3. Weaker shielding effect of d -electrons of Ga
4. Stronger shielding effect of d -electrons of Ga

Answer: 3. Weaker shielding effect of d -electrons of Ga

Question 17. Carbon does not form complexes, because

1. Vacant d – orbitals are absent in it
2. It is not a metal
3. Its atomic radius is small
4. It is neutral

Answer: 1. Vacant d -d-orbitals are absent in it

Question 18. Supercritical CO₂ is used as

1. Dry ice
2. Fire extinguisher
3. A solvent for the extraction of organic compounds from natural sources
4. The inert solvent in various reactions

Answer: 3. Asolvent for the extraction of organic compounds from natural sources

Question 19. The stability of the +1 oxidation state increases in the sequence—

1. Al < Ga < In < Tl
2. Tl<In<Ga<Al
3. In < Tl < Ga < Al
4. Ga<In<Al<Tl

Answer: 1. Al < Ga < In < Tl

Question 20. Which ofthe following is acidic—

1. B₂O₃
2. Al₂O₃
3. Ga₂O₃
4. ln₂O₃

Answer: 1.B₂O₃

Question 21. The correct order of first ionisation enthalpy for Gr-13 elements is

1. B > Al > Ga > In > Tl
2. B < Al < Ga < In < Tl
3. B < Al > Ga < In > Tl
4. B > Al < Ga > In < Tl

Answer: 4.  B > Al < Ga > In < Tl

Question 22. Which of the following elements is not likely to be the central atom in MF^3-₆

1. B
2. Al
3. Ga
4. In

Answer: 1. B

Question 23. The tendency of catenation in Gr-14 elements follows the order

1. C > Si > Ge > Sn
2. C>>Si > Ge s: Sn
3. Si > C > Sn > Ge
4. Ge > Sn > Si > C

Answer: 2. C>>Si > Ge s: Sn

Question 24. The repeating structural unit in silicone is—

Answer: 2

Question 25. Which of the following allotropic forms of carbon is isomorphous with crystalline silicon

1. Graphite
2. Coal
3. Coke
4. Diamond

Answer: 4.  Diamond

Question 26. The shape and hybridisation of the B-atom of BH₄^– is

1. Pyramidal, sp³
2. Octahedral, sp³d²
3. Tetrahedral, sp³
4. None of these

Answer: 3.  Tetrahedral, sp³

Question 27. Germanium is transparent in

1. Visible light
2. Infrared region
3. Ultraviolet region
4. Ultraviolet region

Answer: 2. Infrared region

Question 28. The chain length of silicone polymer can be controlled by adding

1. MeSiCl₃
2. Me₂SiCl₂
3. Me₃SiCl
4. Me₄Si

Answer: 3. Me₃SiCl

Question 29. Higher B—F (in BF₃) bond dissociation energy as compared to that of C— F (in CF₄) is due to

1. Stronger σ-bond between B and F in BF₃ as compared to that between C and F in CF₄
2. Significant pn-pn interaction between B and F in
3. BF₃ whereas there is no possibility of such interaction between C and F in CF₄
4. A lower degree of pπ-pπ interaction between B and F in BF₃ than that between C and F in CF₄ smaller size of B -atom as compared to that of C -atom

Answer: 2. Significant pn-pn interaction between B and F in

Question 30. The reaction of diborane with ammonia initially gives

1. B₂H₆.NH₃
2. Borazol
3. B₂H₆-3NH₃
4. [BH₂(NH₃)₂]⁺[BH₄]^–

Answer: 4.  [BH₂(NH₃)₂]⁺[BH₄]^–

Question 31.    X, y, Z and their respective colours are

1. X = Cu(BO₂)₂ (blue), Y = Cu(BO₂) (colourless),Z = Cu (red)
2. X = CuBOz (blue) , Y = Cu(BO₂)₂ (colourless), Z = Cu (Black)
3. X = CU(BO₂)₂ (red) , Y = CuBO₂ (blue) Z = (red)
4. X = Cu (red) , Y = Cu(BO₂)₂ (blue) , Z = CuBO₂ (colourless)

Answer: 1. X = Cu(BO₂)₂ (blue) , Y = Cu(BO₂) (colourless) ,Z = Cu (red)

Question 32. The correct formula for borax is

1. Na₂[B₄O₄(OH)₃].9H₂O
2. Na₂[B₄O₄(OH)₄].8H₂O
3. Na₂[B₄O₆(OH)₅].7H₂O
4. Na₂[B₄O₇(OH)₆]-6H₂O

Answer: 2. Na₂[B₄O₄(OH)₄].8H₂O

Question 33. Which of the following statements is correct—

1. Sn (II) and Pb (IV) salts are used as oxidants
2. Sn (II) and Pb (IV) salts are used as reductants
3. Sn (II) salts are used as oxidants and Pb (IV) salts are used as reductants
4. Sn (II) salts are used as reductants and Pb (IV) salts are used as oxidants

Answer: 4. Sn (II) salts are used as reductants and Pb (IV) salts are used as oxidants

Question 34. SiCl₄ gets readily hydrolysed but CCl₄ does not, because

1. Si can expand its octet but C does not
2. The ionisation enthalpy of C is greater than that of Si
3. C forms both double and triple bonds
4. The electronegativity of C is greater than that of Si

Answer: 1. Si can expand its octet but C does not

Question 35. PbCl₄ exists but PbBr₄ and Pbl₄ do not, because

1. Chlorine is a most electronegative element
2. Bromine and iodine are larger
3. Bromine and iodine cannot oxidise Pb to Pb⁴⁺
4. Bromine & iodine are stronger oxidants than chlorine

Answer: 3. Bromine and iodine cannot oxidise Pb to Pb⁴⁺

Question 36. Which of the following resembles CO in terms of physical properties

1. O₂
2. Cl₂
3. N₂
4. F₂

Answer: 3.N₂

Question 37. Which ofthe following statements is incorrect

1. Most of the silicones are water repellents
2. Silicones get dissociated at high temperature
3. Silicones do not get oxidised in air at high temperature
4. Silicones are good thermal and electrical insulators

Answer: 2.  Silicones get dissociated at high temperature

Question 38. Wollastonite is a

1. Three-dimensional silicate
2. Chain silicate
3. Sheet silicate
4. Cyclic silicate

Answer: 4. Cyclic silicate

Question 39. B(OH)₃ + NaOH ⇌ NaBO₂ + Na[B(OH)₄] + H₂O; The above reaction be made to proceed in the forward direction by

1. Addition of diol
2. Addition of borax
3. Addition of KHF₂
4. Addition of NaHPO₄

Answer: 1. Addition of diol

Question 40. Which ofthe following is correct

1. Al(OH)₃ is more acidic than B(OH)₃
2. B(OH)₃ is basic but Al(OH)₃ is amphoteric in nature
3. B(OH)₃ is acidic but Al(OH)₃ is amphoteric in nature
4. Both B(OH)₃ and Al(OH)₃ are amphoteric

Answer: 3. B(OH)₃ is acidic but Al(OH)₃ is amphoteric in nature

Question 41. Which of the following is correct

1. B₂H₆-2NH₃ is known as inorganic benzene
2. Boric acid is a protonic acid
3. Be exhibits coordination number = 6
4. BeCl₃ and AlCl₃ have bridged chlorine structures in the solid phase

Answer: 4. BeCl₃ and AlCl₃ have bridged chlorine structures in the solid phase

Question 42. B cannot form B³⁺ ion, because

1. Formation of B³⁺ ion requires a greater amount of energy and this cannot be obtained from lattice energy or hydration energy
2. B is a non-metal
3. B do not possess any vacant d -orbitals
4. B possess the highest melting point among its group members

Answer: 1.  Formation of B³⁺ ion requires a greater amount of energy and this cannot be obtained from lattice energy or hydration energy

Question 43. Which of the following has the minimum heat of dissociation

1. (CH₃)₃N : → BF₃
2. (CH₃)₃N :→B(CH₃)₂F
3. (CH₃)₃N :→ B(CH₃)₃
4. (CH₃)₃N :→B(CH₃)F₂

Answer: 3. (CH₃)₃N :→ B(CH₃)₃

Question 44. The correct statement concerning CO is

1. It combines with H₂O to give carbonic acid
2. It reacts with haemoglobin
3. It acts only as a reducing agent
4. It cannot form adducts

Answer: 2.  It reacts with haemoglobin

Question 45. Foamite mixture consists of

1. Al₂ (SO₄)₃ + NaHCO₃
2. Al₂(SO₄)₃ + Na₂CO₃
3. Fe₂(SO₄)₃ + Na₂CO₃
4. CuSO₄ + NaHCO₃

Answer: 1. Al₂ (SO₄)₃ + NaHCO₃

Question 46. In which of the following compounds, the 3c-2e bond is present

1. AI₂(CH₃)₆
2. In (C₆H₅)₃
3. B₂H₆
4. Al₂Cl₆

Answer: 1 and 2

Question 47. Which ofthe following oxides do not get reduced by CO

1. ZnO
2. Fe₂O₃
3. CaO
4. Na₂O

Answer: 1 and 3

Question 48. Which of the following is not isostructural with CO₂

1. SnCl₂
2. HgCl₂
3. SCl₂
4. Znl₂

Answer: 2 and 4

Question 49. C(OH₄) is unstable but Si(OH)₄ is stable. Possible reasons are

1. C — O bond energy is low
2. C — O  bond energy is high
3. Si — O bond energy is low
4. Si — O bond energy is high

Answer: 1 and 4

Question 50. Which ofthe following statements are correct

1. Fullerenes have dangling bonds
2. Fullerenes are cage-like molecules
3. Graphite is thermodynamically the most stable allotrope of carbon
4. Graphite is the purest allotrope of carbon

Answer: 2 and 3

Question 51. Boron trifluoride (BF₃) is

1. An electron-deficient compound
2. A Lewis acid
3. An ionic compound
4. Used as rocket fuel

Answer: 1 and 2

Question 52. Compounds which readily undergo hydrolysis are

1. AlCl₃
2. CCl₄
3. SiCl₄
4. PbCl₄

Answer: 1, 3 and 4

Question 53. Which of the following compounds undergo disproportionation in aqueous solution

1. TlCl₃
2. GaCl
3. InCl
4. TlCl

Answer: 2 and 3

Question 54. Me₃SiCl is used during the polymerisation of organosilicon because

1. The chain length of organosilicon polymers can be controlled by adding Me₃SiCl
2. Me₃SiCl blocks the end terminal of the silicone polymer
3. Me₃SiCl improves the quality and yield of the polymer
4. Me₃SiCl acts as a catalyst during polymerisation

Answer: 1 and 2

Question 55. Which of the following acids, on dehydration, produce oxides of carbon

1. Succinic acid
2. Propanoic acid
3. Mlonicacid
4. Formic acid

Answer: 3 and 4

Question 56. Which of the following are basic nature

1. B₂O₃
2. Tl₂O
3. ln₂O₃
4. Al₂O₃

Answer: 2 and 3

Question 57. The linear shape of CO₂ is due to

1. sp³ -hybridisation of C
2. sp -hybridisation of C
3. pπ-pπ bonding between C and 0
4. sp² -hybridisation of C

Answer: 2 and 3

Question 58. Which metallic salts exhibit the same colouration both in oxidising and reducing flame in the borax-bead test

1. Fe
2. Mn
3. Co
4. Cr

Answer: 3 and 4

Question 59. Which of the following two acidic substances react to give an alkaline solution

1. H₂B₄O₇
2. H₃BO₃
3. HF
4. KHF₂

Answer: 2 and 4

Question 60. Which of the following are the ingredients of baking powder

1. NaOH
2. Tartaric acid
3. Formic acid
4. Potassium hydrogen tartrate

Answer: 2 and 4

Question 61. Which ofthe following are sheet silicates

1. Diopside
2. Kaolinite
3. Talc
4. Beryl

Answer: 2 and 3

Question 62. Identify the correct resonating structures

1. O -C ≡ O
2. O = C = O
3. O ≡ C –  O⁺
4. ^–O – C ≡  O⁺

Answer: 2 and 4

Question 63. Which of the following species are not known

1. [SiCl₆]^2-
2. [CF₆]^2-
3. [PbCl₆]^2-
4. [SiF₆]^2-

Answer: 2 and 3

Question 64. Which of the following is correct concerning Gr-14 elements

1. Stability of dihalides: CX₂ > SiX₂ > GeX₂ > SnX₂
2. The tendency to form pπ-pπ multiple bonds increases down the group
3. The tendency of catenation decreases down the group
4. Each of them forms oxide ofthe type MO₂

Answer: 2, 3 and 4

Question 65. Which ofthe following has a bridge bond

1. Water
2. Inorganic benzene
3. Phenol
4. Diborane

Answer: 4. Diborane

Question 66. An aqueous solution of borax is

1. Neutral
2. Amphoteric
3. Basic
4. Acidic

Answer: 3. Basic

An aqueous solution of borax is basic because it is a salt of strong base (NaOH) and weak acid (H₃BO₃)

Question 67. Boric acid is polymeric due to

1. Its acidic nature
2. The presence of hydrogen bonds
3. Its monobasic nature
4. Its geometry

Answer: 2. The presence of hydrogen bonds

Boric acid is polymeric due to the presence of; hydrogen bonds

Question 68. The type of hybridisation of boron In dlborane

1. sp
2. sp²
3. sp³
4. dsp²

Answer: 2.sp²

In B₂HO, the hybridisation state of B is sp²

Question 69. Thermo dynamically the most stable form of carbon is

1. Diamond
2. Graphite
3. Fullerenes
4. Coal

Answer: 2. Graphite

Question 70. Elements of Gr-14

1. Exhibit oxidation state of +4 only
2. They exhibit oxidation state of +2 and +4
3. Form M^2-and M²⁺Ions
4. Form M²⁺ and M⁴⁺ ions

Answer: 2. They exhibit oxidation states of +2 and +4

Elements of group 14 exhibit oxidation states of +2 and +4 due to the inert pair effect