250+ TOP MCQs on Applications of Equilibrium Constants and Answers

Chemistry Multiple Choice Questions on “Applications of Equilibrium Constants”.

1. If K_C > 10x, the products predominate over reactants. Then what is the value of x?
a) 2
b) 3
c) 4
d) 1
Answer: b
Clarification: If K_C > 10x, the products are predominant, over the reactants in a chemical reaction because if K_C is very large the reaction proceeds nearly to completion an example for this is at 300K, H_2(g) + Cl_2(g) (rightleftharpoons) 2HCl_(g), K_C = 4 x 10³¹.

2. What will happen if K_C > 10^-3 in a chemical reaction?
a) products are predominant
b) reactants are predominant
c) equilibrium
d) dynamic equilibrium
Answer: d
Clarification: If K_C > 10^-3, the reactants are predominant over the products in a chemical reaction and the products are predominant, over the reactants in a chemical reaction, if K_C > 10³, where K_C is the equilibrium constant.

3. Reaction quotient is depicted by this symbol __________
a) K
b) Q_C
c) R
d) q
Answer: b
Clarification: For any reversible reaction at any stage other than equilibrium, the ratio of the molar concentrations of the products to that of the reactants, where is concentration term is raised to the power equal to the stoichiometric efficient to the substance concerned is called the reaction quotient, Q_C.

4. For a reaction aA + bB → cC + dD, which is not in equilibrium the Q_C is given as __________
a) [A]^a[B]^b/[C]^c[D]^d
b) [C]^c[D]^d/[A]^a[B]^b
c) [A][B]/[C][D]
d) [C][D]/[A][B]
Answer: b
Clarification: A very basic reaction like aA + bB → cC + dD, where the capital letters represent the compounds or molecules and the small letters are the coefficients of them the reaction quotient Q_C, is given by [C]^c[D]^d/[A]^a[B]^b.

5. What will happen If Q_C > K_C?
a) Q_C decreases till equilibrium
b) Q_C increases till equilibrium
c) Q_C remains constant
d) cannot say
Answer: a
Clarification: If Q_C > K_C, the value of Q_C will tend to decrease to reach the value of equilibrium constant (that is towards equilibrium) and the reaction will continue in the opposite direction, where Q_C is reaction quotient and K_C is the equilibrium constant.

6. At equilibrium, K_C is _______________
a) greater than reaction quotient
b) equal to the reaction quotient
c) less than the reaction question
d) independent of reaction question
Answer: b
Clarification: At equilibrium, the equilibrium constant and the reaction quotient is equal. The equilibrium constant is depicted by the symbol K_C and the reaction quotient is represented by the symbol Q_C.

7. What do you think will happen if reaction quotient is smaller than the equilibrium constant?
a) equilibrium constant will change
b) reaction quotient remains constant
c) reaction quotient increases continuously
d) reaction quotient increases till K_C
Answer: d
Clarification: If the reaction quotient is less than the equilibrium constant K_C, the reaction quotient will tend to increase and the reaction will proceed in the forward direction, till it reaches the value of the equilibrium constant.

8. If [H₂]t=0.10 M, [I₂]t = 0.20 M and [HI]t = 0.40 M, in the reaction H_2(g) + I_2(g) (rightleftharpoons) 2HI_(g), what is the value of Q_C?
a) 8
b) 4
c) 2
d) 1
Answer: a
Clarification: We know that reaction quotient Q_c = [HI]t² / [H₂]t[I₂]t and given that [H₂]t=0.10 M, [I₂]t = 0.20 M and [HI]t = 0.40 M, So by substituting, we get Q_c = (0.40 M x 0.40 M)/(0.20 M x 0.10 M) = 8.0, 8 is the answer.

9. What do you understand from the reaction if reaction quotient is 2 and the equilibrium constant is 3?
a) the equilibrium constant increases
b) the equilibrium constant decreases
c) the equilibrium constant remains the same
d) reaction quotient increases
Answer: d
Clarification: In a reaction, if reaction quotient is less than the equilibrium constant, the reaction quotient will tend to increase and the reaction will proceed in the forward direction till it reaches equilibrium.

10. Equilibrium constant depends on the temperature.
a) true
b) false
Answer: a
Clarification: Yes, the equilibrium constant depends on the temperature and its unique for a chemical reaction at a given temperature. So the above-given statement about the equilibrium constant is considered to be true.