CBSE Class 11 Chemistry Chemical Equilibrium MCQs Set G

Question. Equimolar solutions of the following were prepared in water separately. Which one of the solutions will record the highest pH?
(a) CaCl₂
(b) SrCl₂
(c) BaCl₂
(d) MgCl₂

Answer: c

Question. Conjugate base for Bronsted acids H₂O and HF are
(a) H₃O⁺ and H₂F⁺, respectively
(b) OH^– and H₂F⁺, respectively
(c) H₃O⁺ and F^–, respectively
(d) OH^– and F^–, respectively.

Answer: d

Question. Which of the following fluoro-compounds is most likely to behave as a Lewis base?
(a) BF₃
(b) PF₃
(c) CF₄
(d) SiF₄ 

Answer: b

Question. Buffer solutions have constant acidity and alkalinity because
(a) They have large excess of H⁺ or OH^– ions
(b) They have fixed value of pH
(c) These give unionised acid or base on reaction with added acid or alkali
(d) Acids and alkalies in these solutions are shielded from attack by other ions 

Answer: c

Question. The dissociation constants for acetic acid and HCN at 25°C are 1.5 × 10^–5 and 4.5 × 10^–10 respectively. The equilibrium constant for the equilibrium, CN^– + CH₃COOH HCN + CH₃COO^– would be
(a) 3.0 × 10^–5
(b) 3.0 × 10^–4
(c) 3.0 × 10⁴
(d) 3.0 × 10⁵ 

Answer: c

Question. Which of the following molecualr species has unpaired electrons?
(a) N₂
(b) F₂
(c) O^–₂
(d) O₂^-2

Answer: c

Question. Which of the following solutions will have pH close to 1.0?
(a) 100 mL of M/10 HCl + 100 mL of M/10 NaOH
(b) 55 mL of M/10 HCl + 45 mL of M/10 NaOH
(c) 10 mL of M/10 HCl + 90 mL of M/10 NaOH
(d) 75 mL of M/10 HCl + 25 mL of M/10 NaOH

Answer: d

Question. An amount of solid NH₄HS is placed in a flask already contaniing ammonia gas at a certain temperature and 0.50 atm pressure. Ammonium hydrogen sulphide decomposes to yield NH₃ and H₂S gases in the flask. When the decomposition reaction reaches equilibrium , the total pressure in the flask rises to 0.84 atm? The equilibrium constant for NH₄HS decomposition at this temperature is
(a) 0.11
(b) 0.17
(c) 0.18
(d) 0.30 

Answer: a

Question. pH value of which one of the following is NOT equal to one?
(a) 0.1 M CH₃COOH
(b) 0.1 M HNO₃
(c) 0.0₅ M H₂SO₄
(d) 50 cm³ 0.4 M HCl + 50 cm³ 0.2 M NaOH 

Answer: a

Question. 1 M NaCl and 1 M HCl are present in an aqueous solution. The solution is
(a) Not a buffer solution with pH < 7
(b) Not a buffer solution with pH > 7
(c) A buffer solution with pH < 7
(d) A buffer solution with pH > 7 

Answer: a

Question. When the rate of formation of reactants is equal to the rate of formation of products, this is known as,
(a) chemical reaction
(b) chemical equilibrium
(c) chemical kinetics
(d) none of these.

Answer: b

Question. It is not possible to attain equilibrium in
(a) closed system
(b) isolated system
(c) open system
(d) none of these.

Answer: c

Question. Which of the following is a characteristic of reversible reaction?
(a) It never proceeds to completion.
(b) It can be influenced by a catalyst.
(c) It proceeds only in the forward direction.
(d) Number of moles of reactants and products are equal. 

Answer: a

Question. The K_sp for Cr (OH)₃ is 1.6 × 10^-30. The molar solubility of this compound in water is:
(a) √ (1.6 × 10^-30)
(b) (√(1.6 × 10^-30))^(1/4)
(c) (√(1.6 × 10^-30)/(27)))^(1/4)
(d) (1.6 × 10^-30)/(27)

Answer: c

Question. In a chemical equilibrium the rate constant of backward reaction is 3.2 × 10^–2 and the equilibrium constant is 2–5. The rate constant of forward reaction is
(a) 1 × 10^–3
(b) 2 × 10^–2
(c) 8 × 10^–2
(d) 4 × 10^–2 

Answer: a

Question. When two reactants, A and B are mixed to give products C and D, the reaction quotient, Q, at the initial stages of the reaction
(a) is zero
(b) Decreases With Time
(c) Is Independent Of Time
(d) Increases With Time

Answer: d

Question. What is the pH of a 0.10 M solution of barium hydroxide, Ba (OH)₂?
(a) 11.31
(b) 11.7
(c) 13.30
(d) None of these

Answer: c

Question. The solubility product of aluminium sulphate is given by the expression
(a) 4s³
(b) 6912s⁷
(c) s²
(d) 108s⁵

Answer: d

Question. For the reversible reaction,
A_(s) + B_(g) C_(g) + D_(g), ΔG° = –350 kJ,
which one of the following statements is true?
(a) The reaction is thermodynamically nonfeasible.
(b) The entropy change is negative.
(c) Equilibrium constant is greater than one.
(d) The reaction should be instantaneous. 

Answer: c

Question. Which of the following is not a characteristic of equilibrium?
(a) Rate is equal in both directions.
(b) Measurable quantities are constant at equilibrium.
(c) Equilibrium occurs in reversible condition.
(d) Equilibrium occurs only in an open vessel at constant temperature

Answer: d

Question. The value of ΔH for the reaction X2_(g) + 4Y_2(g) ⇌ 2XY_4(g) is less than zero. Formation of XY_4(g) will be favoured at
(a) high temperature and high pressure
(b) low pressure and low temperature
(c) high temperature and low pressure
(d) high pressure and low temperature.

Answer: d

Question. Equilibrium constants are given for the following reactions. Out of the following, which is farthest towards completion?
(a) K = 100
(b) K = 0.1
(c) K = 0.01
(d) K = 1 

Answer: a

Question. In a reversible chemical reaction at equilibrium, if the concentration of any one of the reactants is doubled, then the equilibrium constant will
(a) also be doubled
(b) be halved
(c) remain the same
(d) become one-fourth. 

Answer: c

Question. Which of the following options will be correct for the stage of half completion of the reaction X Y.
(a) ΔG° = 0
(b) ΔG° > 0
(c) ΔG° < 0
(d) ΔG° = –RT ln2

Answer: a

Question. Which will make basic buffer?
(a) 100 mL of 0.1 M HCl + 100 mL of
0.1 M NaOH
(b) 50 mL of 0.1 M NaOH + 25 mL of
0.1 M CH₃COOH
(c) 100 mL of 0.1 M CH₃COOH + 100 mL of
0.1 M NaOH
(d) 100 mL of 0.1 M HCl + 200 mL of
0.1 M NH₄OH

Answer: d

Case Based MCQs :

Le Chatelier’s principle is also known as the equilibrium law, used to predict the effect of change on a system at chemical equilibrium. This principle states that equilibrium adjust the forward and backward reactions in such a way as to accept the change affecting the equilibrium condition. When factor like concentration, pressure, temperature, inert gas that affect equilibrium are changed, the equilibrium will shift in that direction where the effects that caused by these changes are nullified. This principle is also used to manipulate reversible reaction in order to obtain suitable outcomes.

Question. For the reversible reaction,
N_2(g) + 3H_2(g) 2NH_3(g) + heat
The equilibrium shifts in forward direction
(a) by increasing the concentration of NH_3(g) 
(b) by decreasing the pressure
(c) by decreasing the concentrations of N_2(g) and H_2(g)
(d) by increasing pressure and decreasing temperature. 

Answer: d

Question. X + Y ⇌ P + Q
For the above equilibrium, the reactant concentration is doubled, what would happen then to equilibrium constant?
(a) Remains constant
(b) Be doubled
(c) Be halved
(d) Cannot be predicted 

Answer: a

Question. Favourable conditions for manufacture of ammonia by the reaction,
N₂ + 3H₂ ⇌ 2NH₃; ΔH = – 21.9 kcal are
(a) low temperature, low pressure and catalyst
(b) low temperature, high pressure and catalyst
(c) high temperature, low pressure and catalyst
(d) high temperature, high pressure and catalyst. 

Answer: b

Question. Which one of the following conditions will favour maximum formation of the product in the reaction
A_2(g) + B_2(g) X_2(g), Δr H = –X kJ ?
(a) Low temperature and high pressure
(b) Low temperature and low pressure
(c) High temperature and high pressure
(d) High temperature and low pressure

Answer: a

Question. In which one of the following equilibria will the point of equilibrium shift to left when the pressure of the system is increased?
(a) H_2(g) + I_2(g) ⇌ 2HI_(g)
(b) 2NH_3(g) ⇌ N_2(g) + 3H_2(g)
(c) C_(s) + O_2(g) ⇌ CO_2(g)
(d) 2H_2(g) + ⇌ O_2(g) 2H₂O_(g)

Answer: b