Chapter 6: Equilibrium — Online MCQ Test
CHEMISTRY · Grade 11 · CBSE(NCERT)
Practice Chapter 6: Equilibrium with a free chapter-wise online MCQ test.
This chapter covers: Chemical equilibrium Physical equilibrium Equilibrium constant Le Chateliers principle Ionic equilibrium pH Buffer solution Acid Base Solubility product.
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Chapter 6: Equilibrium — Important Questions & Answers
What is meant by chemical equilibrium?
- A. A state in which reactants are completely consumed
- B. A state in which the rates of forward and backward reactions are equal
- C. A state in which only the forward reaction occurs
- D. A state in which the reaction stops permanently
Answer: B. A state in which the rates of forward and backward reactions are equal
In chemical equilibrium, both forward and backward reactions continue, but their rates become equal, so the concentrations remain constant.
In chemical equilibrium, both forward and backward reactions continue, but their rates become equal, so the concentrations remain constant.
Which of the following is an example of physical equilibrium?
- A. N2 + 3H2 ⇌ 2NH3
- B. CaCO3(s) ⇌ CaO(s) + CO2(g)
- C. H2O(l) ⇌ H2O(g) in a closed container
- D. HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
Answer: C. H2O(l) ⇌ H2O(g) in a closed container
Physical equilibrium involves phase changes, such as liquid-vapour equilibrium in a closed container.
Physical equilibrium involves phase changes, such as liquid-vapour equilibrium in a closed container.
For the equilibrium H2(g) + I2(g) ⇌ 2HI(g), if the concentration of HI is increased, the equilibrium will shift:
- A. To the right
- B. To the left
- C. No shift
- D. Cannot be predicted
Answer: B. To the left
Adding product makes the system shift in the reverse direction to consume the excess HI.
Adding product makes the system shift in the reverse direction to consume the excess HI.
For the reaction PCl5(g) ⇌ PCl3(g) + Cl2(g), which action will shift equilibrium to the right?
- A. Adding Cl2
- B. Increasing pressure
- C. Removing PCl3
- D. Decreasing temperature if the forward reaction is endothermic
Answer: C. Removing PCl3
Removing a product causes the equilibrium to shift right to produce more products.
Removing a product causes the equilibrium to shift right to produce more products.
Which of the following is the most appropriate explanation for why HCl is not used to make a buffer with CH3COOH?
- A. HCl is a weak acid
- B. HCl is a strong acid and has no conjugate base to provide buffering action
- C. HCl reacts only with bases, not acids
- D. HCl increases pH too much
Answer: B. HCl is a strong acid and has no conjugate base to provide buffering action
A buffer requires a weak acid and its conjugate base or a weak base and its conjugate acid; HCl does not provide a weak conjugate pair.
A buffer requires a weak acid and its conjugate base or a weak base and its conjugate acid; HCl does not provide a weak conjugate pair.