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Chapter 7, Equilibrium, is an essential part of e Class 11 Chemistry MCQs, and here you will find multiple-choice questions (MCQ) with answers based on the CBSE syllabus and the latest curriculum. These MCQs are designed to help students revise the key concepts of the chapter effectively. Practicing these questions enables students to strengthen their understanding, prepare for Class 11 annual exams, and perform well in competitive exams like NEET and JEE.
Class 11 Equilibrium MCQs – Question with Answers
1. What is the equilibrium constant (K) dependent on?
a) Concentration
b) Pressure
c) Temperature
d) Volume
Answer: c) Temperature
2. Which condition defines a system in equilibrium?
a) All reactions stop
b) Forward and backward reaction rates are equal
c) Only forward reaction occurs
d) Only backward reaction occurs
Answer: b) Forward and backward reaction rates are equal
3. Which of the following does not affect the equilibrium state?
a) Catalyst
b) Temperature
c) Pressure
d) Concentration
Answer: a) Catalyst
4. Le Chatelier’s principle predicts that adding heat to an exothermic reaction will:
a) Shift the equilibrium to the right
b) Shift the equilibrium to the left
c) Have no effect
d) Stop the reaction
Answer: b) Shift the equilibrium to the left
5. What happens to the equilibrium constant when pressure is increased in a reaction with more gaseous products?
a) Increases
b) Decreases
c) Remains unchanged
d) Depends on the catalyst
Answer: c) Remains unchanged
6. What is the value of \( K_p \) when \( K_c = 1 \) and Δn = 0?
a) 1
b) 0
c) Depends on pressure
d) Infinity
Answer: a) 1
7. If \( Q_c < K_c \), the reaction will:
a) Move forward
b) Move backward
c) Be at equilibrium
d) Stop
Answer: a) Move forward
8. Which of the following is a characteristic of equilibrium?
a) Dynamic nature
b) Complete reaction
c) No reverse reaction
d) Irreversible process
Answer: a) Dynamic nature
9. What happens to the equilibrium constant if a reaction is reversed?
a) It is squared
b) It is inverted
c) It doubles
d) No change
Answer: b) It is inverted
10. The pH of a neutral solution at 25°C is:
a) 7
b) 0
c) 14
d) 1
Answer: a) 7
11. In a buffer solution of weak acid and its salt, the pH depends on:
a) Acid concentration only
b) Salt concentration only
c) Ratio of salt to acid concentrations
d) Only water concentration
Answer: c) Ratio of salt to acid concentrations
12. When a catalyst is added to a reaction at equilibrium, it:
a) Changes the equilibrium constant
b) Increases the forward rate only
c) Speeds up both forward and reverse reactions equally
d) Has no effect
Answer: c) Speeds up both forward and reverse reactions equally
13. The value of \( K_c \) for a reaction at equilibrium is 10. If the concentration of the reactant is doubled, \( K_c \):
a) Becomes 20
b) Becomes 5
c) Remains 10
d) Doubles
Answer: c) Remains 10
14. If the pH of a solution is 3, its hydrogen ion concentration is:
a) \( 10^{-3} \) mol/L
b) \( 10^3 \) mol/L
c) 3 mol/L
d) \( 10^{-1} \) mol/L
Answer: a) \( 10^{-3} \) mol/L
15. Which expression relates \( K_p \) and \( K_c \)?
a) \( K_p = K_c (RT)^{-\Delta n} \)
b) \( K_p = K_c \times RT \)
c) \( K_p = K_c \)
d) \( K_p = RT / K_c \)
Answer: a) \( K_p = K_c (RT)^{-\Delta n} \)
16. Which of these is a strong acid?
a) HCl
b) CH3COOH
c) H2CO3
d) HCN
Answer: a) HCl
17. When a solution’s pH is less than 7, it is:
a) Basic
b) Neutral
c) Acidic
d) Neither
Answer: c) Acidic
18. A reaction has ΔH > 0 and ΔS > 0. It will be spontaneous when:
a) High temperature
b) Low temperature
c) At any temperature
d) Never spontaneous
Answer: a) High temperature
19. The pOH of a solution is 5. Its pH will be:
a) 5
b) 9
c) 14
d) 7
Answer: b) 9
20. In a chemical equilibrium, what is true about reactants and products?
a) Their concentrations are equal
b) Their rates of formation are equal
c) Both are consumed completely
d) The reaction stops
Answer: b) Their rates of formation are equal
Class 11 Chemistry MCQ FAQs
Is equilibrium hard in Class 11?
Equilibrium can feel tricky at first because it involves concepts like reversible reactions, equilibrium constant, and Le Chatelier’s principle. However, with regular practice and a clear understanding of the basic concepts, it becomes manageable.
What does it indicate having a higher equilibrium constant?
A higher equilibrium constant (K) means that the products are favored over the reactants at equilibrium. In simpler terms, most of the reactants have been converted into products.
What does the dynamic equilibrium mainly concern about?
Dynamic equilibrium focuses on the balance between the forward and reverse reactions. Even though the reactions continue to happen, their rates are equal, so the concentrations of reactants and products remain constant.
Is equilibrium important for NEET?
Yes, equilibrium is very important for NEET. It forms the foundation for understanding many chemical processes, acid-base reactions, and thermodynamics, all of which frequently appear in NEET exams.
What is Le Chatelier's principle for NEET?
Le Chatelier's principle states that if a system at equilibrium is disturbed (by changing concentration, temperature, or pressure), it will adjust itself to counteract the disturbance and restore equilibrium.
Which of the following doesn't happen when a system is at equilibrium state?
At equilibrium: The concentrations of reactants and products remain constant. The forward and backward reaction rates are equal. What doesn’t happen: The reaction doesn’t stop. It continues dynamically.
What is vector MCQ?
Vector MCQ refers to multiple-choice questions about vectors, which involve magnitude and direction. These questions typically test your understanding of concepts like vector addition, subtraction, resolution, and their applications.
What are the conditions for equilibrium (MCQ)?
The key conditions for equilibrium are: The rates of forward and backward reactions are equal. The system is closed (no reactants or products can escape). The macroscopic properties (like concentration, pressure, etc.) remain constant over time.
