CBSE Class 11 Chemistry Chemical Equilibrium MCQs Set 06

Question. The species among the following, which can act as an acid and a base is 
(a) HSO^–₄
(b) SO^2-₄
(c) H₃O⁺
(d) Cl^–
Answer: a

Question. For a diprotic acid, which of the following is true for 1st and 2nd ionisation constants (Ka₁ and Ka₂) ? 
(a) K_a1 = Ka₂
(b) K_a1 > Ka₂
(c) Ka₂ > K_a1
(d) Ka₂ ≥ K_a1
Answer: b

Question. Water is well known amphoprotic solvent. In which chemical reaction, water is behaving as a base ? 
(a) H₂SO₄ + H₂O → H₃O⁺ + HSO^–₄
(b) H₂O + H₂O → H₃O⁺ + OH^–
(c) H₂O + NH₂ → NH₃ + OH^–
(d) H₂O + NH₃ → NH⁺₄+ OH^–
Answer: a

Question. The pH of a neutral water sample is 6. 5. Then, the temperature of water
(a) is 25°C
(b) is more than 25°C
( c) is less than 25°C
(d) can be more or less than 25°C
Answer: b

Question. A weak monobasic acid is 1 % ionised in 0.1 M solution at 2S’C. The percentage of ionisation in its 0.025 M solution is 
(a) 1
(b) 2
(c) 3 
(d) 4
Answer: b

Question. Which of the following is the weakest acid? 
(a) HCl
(b) HF
(c) H₂SO₄
(d) HNO₃
Answer: b

Question. 1 mole of H₂ and 2 moles of I₂ are taken initially in a 2 L vessel. The number of moles of H₂ at equilibrium is 0.2. Then, the number of moles of I₂ and HI at equilibrium respectively are 
(a) 1.2, 1.6
(b) 1.8, 1.0
(c) 0.4, 2.4
(d) 0.8, 2.0
Answer: a

Questionuestion. Ammonium carbonate decomposes as
NH₂COONH₄(s) ⇌ 2 NH₃ (g) + CO₂ (g)
For the reaction, K_P = 2.9 x 10^-5 atm³ . If we start with 1 mole of the compound, the total pressure at equilibrium would be 
(a) 0.766 atm
(b) 0.0581 atm
(c) 0.0388 atm
(d) 0.0194 atm
Answer: b

Question. According to hard and soft acid-base principle, a hard acid
(a) has low charge density 
(b) shows preference for soft bases
(c) shows preference for donor atoms of low electronegativity
(d) is not polarisable
Answer: d

Question. Four species are listed below
I. HCO^–₃
II. H₃O⁺
III. HSO₄
IV. HSO₃F
Which one of the following is the correct sequence of their acid strength ?
(a) IV < II < III < I
(b) II < III < I < IV
(c) I < III < II < IV
(d) III < I < IV < II
Answer: c

Question. Three reactions involving H₂PO^–₄ are given below
I. H₃PO₄ + H₂O → H₃O⁺ + H₂PO^–₄ 
II. H₂PO^–₄ + H₂O → HPO^2-₄+ H₃O⁺
III. H₂PO^–₄ + OH^– → H₃PO₄ + O^2-
In which of the above does H₂PO^–₄ act as an acid?
(a) Only II
(b) Both I and II 
(c) Only III
(d) Only I
Answer: a

Question. Which of the following behaves as Lewis acid and not as Bronsted acid? 
(a) HCl
(b) H₂SO₄
(c) HSO₃
(d) SO₃
Answer: d 

Question. Which one of the following species acts as both Bronsted acid and base ? 
(a) H₂PO^–₂
(b) HPO^2-₃
(c) HPO^2-₄
(d) All of these
Answer: c

Question. Which of the following is a Lewis acid ? 
(a) Cl^–
(b) H₃O⁺
(c) PF₃
(d) C₂H₅OH
Answer: b

Question. For a concentrated solution ofa weak electrolyte A_xB_Y of concentration C, the degree of dissociation ‘a.’ is given as
(a) a = √K_eq /C(x+ y)
(b) a = √K_eq /C(xy)
(c) a = (K_eq /C^x+y-1 x^X y^Y)^{1/(x + y)}
(d) a = (K_eq /Cxy)
Answer: c

Question. Conjugate acid of HF^–₂ is
(a) H+
(b) HF
(c) F^–₂
(d) H₂F₂ 
Answer: d

Question. Solubility of Al(OH)₃ = s,K_sp will be 
(a) 108S³
(b) 27S³
(c) 4S⁴
(d) 27S⁴
Answer: d

Question. According to Bronsted and Lowry , the strength of an acid depends upon 
(a) the tendency to gain electrons
(b) the tendency to loss protons
(c) the tendency to accept protons
(d) the tendency to loss electrons
Answer: b

Question. Which is a Lewis base?
(a) B₂H₆
(b) LiAIH₄
(c) AIH₃
(d) NH₃
Answer: d

Question. The solubility of Agl in Nal solution is less than that in pure water because 
(a) the temperature of the solution decreases
(b) solubility product of AgI is less than that ofNal
(c) of common ion effect
(d) Agl forms complex with Nal
Answer: c

Question. The solubility product of a sparingly soluble salt AX ₂ is 3.2 x 10^-11 . Its solubility (in mol/L) is 
(a) 5.6 X 10^-6
(b) 3.1 X 10^-4
(c) 2 X 10^-4
(d) 4 X 10^-4
Answer: c

Question. At 90°C, pure water has H₃O⁺ ion concentration of 10^-6 mol / L^-1 . The K_w at 90°C is 
(a) 10^-6
(b) 10^-14
(c) 10^-12
(d) 10^-8
Answer: c

Question. A precipitate of AgCI is formed when equal volumes of the following are mixed.
[ K _sp for AgCI = 10^-10] 
(a) 10^-4 M AgNO₃ and 10^-7 M HCI
(b) 10^-5 MAgNO₃ and 10^-6 MHCI
(c) 10^-5 M AgNO₃ and 10^-4 M HCI
(d) 10^-6 M AgNO₃ and 10^-6 M HCI 
Answer: c

Question. The correct expression for the solubility product of Ca₃ (PO₄)₂ is 
(a) 108s⁵
(b) 27s⁵
(c) 16s⁴
(d) 81s⁴
Answer: a

Question. The solubility product of a salt having general formula MX ₂ , in water is 4 x 10^-2 . The concentration of M²⁺ ions in the aqueous solution of the salt is 
(a) 4.0 x 10^-10 M
(b) 1.6 x 10^-4 M
(c) 1.0 x l0^-4 M
(d) 2.0 x 10^-3
Answer: c

Question. On adding 0.1 M solution each of [Ag⁺], [Ba²⁺],[Ca²⁺] in a Na₂SO₄ solution, species first precipitated is (K_sp BaSO₄ = 10^-11 ,K_sp CaSO₄ = 10^-6, K_sp AgSO₄ =10^-5)
(a) Ag₂SO₄
(b) BaSO₄
(c) CaSO₄
(d) All of the above
Answer: a

Question. For which of the following sparingly soluble salt, the solubility (s)and solubility product (K_sp)are related by the expressions= (K_sp / 4 )^1/3 ? 
(a) BaSO₄
(b) Ca₃ (PO₄)₂
(c) Hg₂Cl₂
(d) Ag₃PO₄
Answer: c

Question. Conjugate base of H₂PO^–₄ is 
(a) H₃PO₄
(b) P₂O₅
(c) PO^3-₄
(d) HPO^2-₄
Answer: d

Question. Diacidic base is
(a) CH₂(OH)₂
(b) Ca(OH)₂
(c) CH₃CH(OH)₂
(d) All of these
Answer: b

Question. Which is Lewis acid? 
(a) BF₃
(b) NF₃
(c) CI^–
(d) H₂O 
Answer: a

Question. In a 500 mL flask, the degree of dissociation of PCl₅ at equilibrium is 40% and the initial amount is 5 moles. The value of equilibrium constant (in mol L^-1 ) for the decomposition of PCl₅ is 
(a) 2.33
(b) 2.66
(c) 5.32
(d) 4.66
Answer: b

Question. CO (g) + 1/2 O₂ (g ) → CO₂ (g) For the above reaction in gaseous phase, the value of K_P / K_c is
(a) (RT)^1/2
(b) (RT)^-1/2 
(c) (RT)
(d) (RT)^-1
Answer: b

Question. In the reaction, H₂( g) + Cl₂(g) ⇌ 2HCl (g ),
(a) K_p ≠ K_c
(b) K_p = K_c
(c) K_p > K_c
(d) K_p < K_c
Answer: b

Question. Which one of the following substances has the highest proton affinity ? 
(a) H₂O
(b) H₂S
(c) NH₃
(d) PH₃
Answer: c

Question. Which is a Lewis base?
(a) B₂H₆
(b) LiAIH₄
(c) AIH₃
(d) NH₃
Answer: d

Question. In Lowry-Bronsted concept, H⁺ donor is known as
(a) acid
(b) base 
(c) Both (a) and (b)
(d) None of these
Answer: a

Question. An example of a Lewis acid is 
(a) MgCI₂
(b) SnCI₄
(c) AICI₃
(d) NaCI
Answer: c

Question. The ionisation of strong compared to water, is
(a) weak, low
(b) strong, more
(c) medium, the same electrolytes in acetic acid,
(d) no ionisation, 100%
Answer: a

Question. An acid solution of 0.005 M has a pH of 5. The degree of ionisation of acid is 
(a) 0.1 x 10^-2
(b) 0.2 x 10^-2
(c) 0.5 x 10^-4
(d) 0.6 x 10^-6
Answer: b

Question. CH₃COOH is weaker acid than H₂SO₄ . It is due to
(a) more ionisation
(b) less ionisation 
(c) covalent bond
(d) electrovalent bond
Answer: b

Question. What is the conjugate base of OH^– ? 
(a) O^2-
(b) O^–
(c) H₂O
(d) O₂
Answer: a

Question. The values of dissociation constant of bases are given below. Which is the weakest base? 
(a) 1.8 X 10^-5
(b) 4.8 X 10^-10
(c) 7.2 X 10^-11
(d) 7.07 x 10^-7
Answer: c

Question. On mixing equal volumes of two buffer solutions of pH value 3 and 5, the pH of the resultant solution will be
(a) 3.3
(b) 4.0 
(c) 4.7
(d) 5.3
Answer: a

Question. Which of the following is not a Lewis acid ? 
(a) BF₃
(b) AICI₃
(c) SO₂
(d) H₂O 
Answer: d

Question. Which one of the following is not an amphoteric substance ?
(a) HNO₃
(b) HCO^–₃
(c) H₂O
(d) NH₃
Answer: a

Question. Conjugate acid of S2O^-2₈ is
(a) H₂S₂O₈
(b) H₂SO₄
(c) HS₂O^–₈
(d) HSO^–₄
Answer: c

Question. Some chemists at ISRO wished to prepare a saturated solution of a silver compound and they wanted it to have the highest concentration of silver ion possible. Which of the following compounds, would they use?
K_sp(AgCl) = 1.8 x 10^-10
K_sp(AgBr) = 5.0 x 10^-13
Ks_p(Ag₂CrO₄) = 2.4 x 10^-12
(a) AgCl
(b) AgBr
(c) Ag₂CrO₄
(d) None of these
Answer: c