Chemical Equilibrium MCQs

Everything tends to achieve minimum energy to remain stable. In a chemical reaction, reactants undergo changes to lower their energy, and the reaction continues until a low-energy state is reached. At chemical equilibrium, the concentrations of reactants and products remain constant over time, resulting in no observable change in the system. In a dynamic equilibrium, the rate of the forward reaction equals the rate of the reverse reaction.

In 0.10 M aqueous solution of pyridine (C₅H₅N), find the percentage of pyridine that forms pyridinium ion (C₅H₅N+H) (Kb for C₅H₅N = 1.7 x 10^-9)

(a) 1.6%
(b) 0.77%
(c) 0.0060%
(d) 0.013%

Find the conjugate acid of NH₂^–

(a) NH₃
(b) NH₄OH
(c) NH₄+
(d) NH₂^–

Find the equilibrium constant of the reaction

If the equilibrium constant for the following reactions are given

(a) K₂K₃/K₁
(b) K1K₃³/K₂
(c) K₂K₃³/K₁
(d) K₂³K3/K₁

8. Find the increase in equilibrium concentration of Fe³⁺ions if OH^–ions concentration decreases to 1/4th in the following reaction

(a) 8 times
(b) 16 times
(c) 4 times
(d) 64 times

Find the pH of a solution when 0.01 M HCl and 0.1 M NaOH are mixed in equal volumes

(a) 12.65
(b) 1.04
(c) 7.0
(d) 2.0

7. What will be the pH of a buffer solution having an equal concentration of B– and HB (Kb = 10^-10for B^–)

(a) 7
(b) 4
(c) 10
(d) 6

On increasing the concentration of reactants in a reversible reaction, then equilibrium constant will

(a) depend on the concentration
(b) increase
(c) unchanged
(d) decrease

Which of the following aqueous solution will be the best conductor of electricity?

(a) NH₃
(b) CH₃COOH
(c) HCl
(d) C₆H₁₂O₆

6. The equilibrium constant is 278 for the reaction

at the same temperature, what will be the equilibrium constant for the following reaction?

(a) 6 x 10^-2
(b) 1.8 x 10^-3
(c) 1.3 x 10^-5
(d) 3.6 x 10^-5

Highest pH will be recorded for which of the following solutions if they are equimolar

(a) AlCl₃
(b) BaCl₂
(c) BeCl₂
(d) LiCl