chemistry : class11 Dynamic Equilibrium : Equilibrium in chemical processes : Equilibrium MCQ Questions and Answers
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Dynamic Equilibrium
MCQ questions and answers.
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MCQ Questions
1. What is meant by dynamic equilibrium in a reversible chemical reaction?
A.
The reaction stops completely
B.
The forward and reverse reactions occur at equal rates
C.
Only the forward reaction occurs
D.
Only the reverse reaction occurs
Correct Answer:
The forward and reverse reactions occur at equal rates
Explanation:
At dynamic equilibrium, the forward and reverse reactions continue simultaneously at equal rates.
2. At dynamic equilibrium, what happens to the concentrations of reactants and products?
A.
They continue to increase indefinitely
B.
They become zero
C.
They remain constant
D.
They become equal
Correct Answer:
They remain constant
Explanation:
The concentrations remain constant because the forward and reverse reactions occur at the same rate.
3. Which statement is correct about a system at dynamic equilibrium?
A.
The reaction has stopped
B.
The forward reaction has stopped
C.
The reverse reaction has stopped
D.
Both forward and reverse reactions are continuing
Correct Answer:
Both forward and reverse reactions are continuing
Explanation:
Dynamic equilibrium is an active state in which both reactions continue, even though there is no overall change in concentration.
4. Dynamic equilibrium can be established only in a:
A.
Reversible reaction
B.
Reaction that produces only gases
C.
Reaction that occurs only once
D.
Reaction with no products
Correct Answer:
Reversible reaction
Explanation:
A reversible reaction is required because both the forward and reverse processes must occur to establish dynamic equilibrium.
5. For the reaction H2(g) + I2(g) ⇌ 2HI(g), what occurs at equilibrium?
A.
Only hydrogen and iodine are present
B.
Only hydrogen iodide is present
C.
Hydrogen, iodine, and hydrogen iodide are present in constant concentrations
D.
The concentrations of all substances become zero
Correct Answer:
Hydrogen, iodine, and hydrogen iodide are present in constant concentrations
Explanation:
At dynamic equilibrium, reactants and products coexist, and their concentrations remain constant while both reactions continue.
6. Why is chemical equilibrium called dynamic?
A.
Because the substances move from one container to another
B.
Because both forward and reverse reactions continue
C.
Because the temperature always increases
D.
Because the reaction occurs only in gases
Correct Answer:
Because both forward and reverse reactions continue
Explanation:
The term dynamic shows that the reaction processes are still occurring in both directions at equilibrium.
7. At dynamic equilibrium, the rate of the forward reaction is:
A.
Greater than the rate of the reverse reaction
B.
Less than the rate of the reverse reaction
C.
Equal to the rate of the reverse reaction
D.
Always zero
Correct Answer:
Equal to the rate of the reverse reaction
Explanation:
Equal forward and reverse reaction rates are the defining feature of dynamic equilibrium.
8. Which observation indicates that a reversible reaction has reached dynamic equilibrium?
A.
The reaction mixture disappears
B.
The concentrations of substances become constant
C.
Only reactants remain
D.
The forward reaction stops permanently
Correct Answer:
The concentrations of substances become constant
Explanation:
Constant concentrations indicate that the forward and reverse reactions are occurring at equal rates.
9. In a closed container, dynamic equilibrium is reached when:
A.
The reactants are completely used up
B.
The products are completely used up
C.
The forward and reverse reaction rates become equal
D.
The temperature becomes zero
Correct Answer:
The forward and reverse reaction rates become equal
Explanation:
A closed system allows products and reactants to remain together, and equilibrium is reached when their reaction rates are equal.
10. Which statement about the amounts of reactants and products at dynamic equilibrium is correct?
A.
Their amounts must always be equal
B.
Their amounts remain constant but need not be equal
C.
The amount of reactants must be zero
D.
The amount of products must be zero
Correct Answer:
Their amounts remain constant but need not be equal
Explanation:
At dynamic equilibrium, the amounts stay constant because the reaction rates are equal, but the amounts of reactants and products do not have to be the same.