CBSE Class 11 Chemistry Chemical Equilibrium MCQs Set E

Question. The solubility in water of a sparingly soluble salt AB₂ is 1.0 x 10^-5 mol L^-1 . Its solubility product number will be
(a) 4 x 10^-15 
(b) 4 X 10^-10
(c) 1 X 10^-15
(d) 1 X 10^-10
Answer: a

Question. The K_sp of Ca₃(PO₄)₂ his
(a) [Ca²⁺] [PO^3-₄]²
(b) [Ca²⁺]³ [PO^3-₄]
(c) [Ca²⁺] [PO^3-₄]
(d) [Ca²⁺]³ [PO^3-₄]²
Answer: d

Question. What is the best description of the change that occurs when Na₂O(s) is dissolved in water? 
(a) Oxidation number of sodium decreases
(b) Oxide ion accepts sharing in a pair of electrons
(c) Oxide ion donates a pair of electrons
(d) Oxidation nwnber of oxygen increases
Answer: c

Question. The solubility of Pb(OH)₂ in water is 6.7 x 10-⁶M. Its solubility in a buffer solution of pH = 8 would be
(a) 1.2 x 10^-2
(b) 1.6 x 10^-3 
(c) 1.6 x 10^-2
(d) 1.2 x 10^-3
Answer: d

Question. If for N₂ + 3H₂ ⇌ 2NH₃ ,K_eq = 1.6x 10^-5 ,thenthe value of K_eq for the reaction NH₃ ⇌ 1/2N₂ + 3/2 H₂will be
(a) 6.25
(b) 25
(c) 250
(d) 500
Answer: c

Question. 2Hl (g) ⇌ H₂ (g) + l₂ (g) – QkJ
For the above reaction, equilibrium constant depends upon
(a) temperature
(b) pressure
(c) catalyst
(d) volume
Answer: a

Question. 3 moles of A and 4 moles of B are mixed together and allowed to come into equilibrium according to the following reaction.
3A (g) + 4B (g) ⇌ 2C (g) + 3D (g)
When equilibrium is reached, there is I mole of C. The equilibrium extent of the reaction is 
(a) 1/ 4
(b) 1/3
(c) 1/2
Answer: c

Question. At a certain temperature, the dissociation constants of formic acid and acetic acid are 1.8 x 10^-4 and 1.8 x l0^-5, respectively. The concentration of acetic acid solution in which the hydrogen ion has the same concentration as in 0.001 M fomlic acid solution is equal to 
(a) 0. 01 M
(b) 0. 001 M
(c) 0. lM
(d) 0. 0001M
Answer: a

Question. The equilibrium constant (K_P) for the decomposition of gaseous H₂O as
H₂O(g) ⇌ H 2 (g) + 1/2 O₂ (g)
is related to degree of dissociation (a) at a total pressure p is given by 
(a) K_p = a³ p^1/2/(1 + α) (2 + α)^1/2
(b) K_p = a³ p^3/2/(1 – α) (2+α)^1/2
(c) K_p = a^3/2 p²/(1 – α) (2 + α)^1/2
(d) K_p = a³ p^1/2/(1 – α) (2+ α)^1/2
Answer: d

Question. On doubling p and V with constant temperature, the equilibrium constant will 
(a) remain constant
(b) become double
(c) become one-fourth
(d) None of the above
Answer: a

Question. At 600° C,K _P for the following reaction is 1 atm.
X(g) ⇌ Y(g)+ Z(g)
At equilibrium, 50% of X ( g) is dissociated. The total pressure of the equilibrium system is p atm. What is the partial pressure (in atm) of X (g) at equilibtium? 
(a) 1
(b) 4
(c) 2
(d) 0.5
Answer: a

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

Question. Which of the following acid is stronger than benzoic acid (K_a = 6.3 X 10^-5)? 
(a) A (K_a = 1.67 x 10^-8)
(b) B (pK_a = 6.0)
(c) C (pK_a = 4.0)
(d) D (K_a = 1.0 x 10^-5) 
Answer: c

Question. For the following three reactions I, II and m, equilibrium constants are given
I. CO (g) + H₂O(g) ⇌ CO₂(g)+ H₂(g),K₁
II CH₄(g)+ H₂O(g) ⇌ CO(g) + 3H₂(g),K₂
III. CH₄(g)+ 2H₂O(g) ⇌ CO₂(g) + 4H₂(g),K₃
Which of the following relations is correct? 
(a) K₁ √K₂ = K₃
(b) K₂ K₃ = K₁
(c) K₃ = K₁ K₂
(d) K₃ K³₂ = K₁²
Answer: c

Question. The equilibrium constants K_Pi and K_Pi for the reactions X ⇌ 2Y and Z ⇌ P + Q, respectively are in the ratio of 1 : 9. If the degree of dissociation of X and Z be equal, then the ratio of total pressure at these equilibria is 
(a) 1 : 36
(b) 1 : 1
(c) 1 : 3
(d) 1 : 9
Answer: a

Question. When ammonium chloride is added to ammonia solution, the pH of the resulting solution will be
(a) increased
(b) seven
(c) decreased
(d) unchanged
Answer: c

Question. The solubility of Sb₂S₃ in water is 1.0 x 10^-5 mol / L at 298 K. What will be its solubility product ?
(a) 108 x 10^-25
(b)1.0 x 10^-25
(c) 144 x 10^-25
(d) 126 x 10^-24
Answer: a

Question. The conjugate acid of NH^–₂ is 
(a) N₂H₄
(b) NH⁺₄
(c) NH₂OH
(d) NH₃
Answer: d

Question. Ostwald’s dilution law is applicable for
(a) weak electrolyte
(b) strong electrolyte
(c) both weak and strong electrolyte
(d) non-electrolyte
Answer: a

Question. If 200 mL of a 0.031 molar solution of H₂SO₄ are added to 84 mL of a 0.150 M KOH solution, what is the value of pH of the resulting solution? 
(a) 12.4
(b) 1.7
(c) 2.2
(d) 10.9
Answer: d

Question. The first and second dissociation constants of an acid H₂A are 1.0 x 10^-5 and 5. 0 x 10^-10 , respectively. The overall dissociation constant of the acid will be 
(a) 5.0 x 10^-5
(b) 5.0 x 10¹⁵
(c) 5.0 x 10^-15
(d) 0.2 x 10⁵ 
Answer: c

Question. If solubility of calcium hydroxide is ✓3, then its solubility product will be 
(a) 27
(b) 3
(c) 9
(d) 12✓3
Answer: d

Question. Which of the following is a Lewis base ? 
(a) NaOH
(b) NH₃
(c) BCI₃
(d) All of these
Answer: b

Question. The solubility product of BaCl₂ is 4 x 10^-9 . Its solubility (in mol/L) is
(a) 4 x 10^-3
(b) 4 x 10^-9
(c) 1 x 10^-3
(d) 1 x 10^-9
Answer: c

Question. The solubility of CaF₂ is pure water is 2.3 x 10^-6 mol dm^-3. Its solubility product will be 
(a) 4.8 x 10^-18
(b) 48.66 x 10^-18
(c) 4.9 x 10^-11
(d) 48.66 x 10^-15
Answer: b

Question. Amines behave as
(a) Lewis acid
(b) Lewis base
(c) aprotic acid
(d) neutral compound
Answer: b

Question. What kind of molecule AICI₃ is?
(a) Bronsted acid 
(b) Lewis acid
(c) Lewis base
(d) Bronsted base
Answer: b

Question. Which of the following is a Lewis acid?
(a) AICI₃
(b) Cl^–
(c) CO
(d) C₂H₂
Answer: a

Question. Metal ions like Ag⁺, Cu²⁺ etc., act as
(a) Bronsted acids
(b) Bronsted bases
(c) Lewis acids
(d) Lewis bases
Answer: c

Question. Which of the following is not a conjugate acid-base pair? 
(a) HPO^3-₃, PO^3-₃
(b) H₂PO^–₄, HPO^2-₄
(c) H₃PO₄ , H₂PO₄
(d) H₂PO^–₄, PO^3-₃
Answer: d

Question. Formaldehyde polymerises to fom1 glucose according to the reaction, 6HCHO ⇌ C₆H₁₂O₆ .
The theoretically computed equilibrium constant for this reaction is found to be 6 x 10²² . If I M solution of glucose dissociates according to the above equilibrium, the concentration of formaldehyde in the solution will be
(a) 1.6x 10^-2 M
(b) 1.6x 10^-4 M 
(c) 1.6 x 10^-6 M
(d) 1.6 x 10^-8 M
Answer: b

Question. 1n chemical equilibrium, the value of Δn (number of molecules of products – number of molecules of reactants), is negative, then the relationship between K_P and K_c will be 
(a) K_p – Kc = 0
(b) K_p = Kc(RT)^+Δmg
(c) K_p = Kc(RT)^-Δm
(d) K_p = KC
Answer: c

Question. Three moles of PCl₅ , three moles of PCl₃ and two moles of Cl₂ are taken in a closed vessel. If at equilibrium, the vessel has 1.5 moles of PCl₅ , the number of moles of PCl₃ present in it is 
(a) 5
(b) 3
(c) 6
(d) 4.5
Answer: d

Question. Strongest conjugate base is
(a) CIO^–
(b) ClO^–₂
(c) ClO^–₃
(d) ClO^–₄
Answer: a

Question. Ammge NH⁺₄ , H₂O, H₃O⁺, HF and Off in increasing order of acidic nature 
(a) H₃O⁺ < NH⁺₄ < HF < OH^– < H₂O
(b) NH⁺₄! < HF < H₃O⁺ < H₂O < OH^–
(c) OH^– < H₂O < NH⁺₄ < HF < H₃O⁺
(d) H₃O⁺> HF > H₂O > NH⁺₄> OH^–
Answer: c

Question. 1.6 moles of PCl₅ (g) is placed in 4 dm³ closed vessel. When the temperature is raised to 500 K, it decomposes and at equilibrium, 1.2 moles of PCl₅ (g) remains. What is the K_c value for the decomposition of PCl₅ (g) into PCl₃ (g) and Cl₂ (g) at 500 K ? 
(a) 0.013
(b) 0.050
(c) 0.033
(d) 0.067
Answer: c

Question. The molar solubility (in mo! L_-1) of a sparingly soluble salt MX ₄ is ‘s’. The corresponding solubility product is K ,_sp. Sis given in terms of K_sp by the relation
(a) S = (K_sp 1/ 28)^1/4
(b) S = (128 K_sp )^1/4
(c) S = (256 K_sp )^1/5
(d) S = (K_sp / 256)^1/5
Answer: d

Question. The value of the ionic product of water depends 
(a) on volume of water
(b) on temperature
(c) changes by adding acid or alkali
(d) always remain constant
Answer: b

Question. Which is a Lewis base?
I₂ + I^– → I^–₃
(a) I₂
(b) I^–₃
(b) I^–
(d) None of these
Answer: c