chemistry : class11 Effect of Temperature : Equilibrium in chemical processes : Equilibrium MCQ Questions and Answers
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Effect of Temperature
MCQ questions and answers.
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MCQ Questions
1. For an endothermic equilibrium reaction, what happens when the temperature is increased?
A.
The equilibrium shifts toward the reactants
B.
The equilibrium shifts toward the products
C.
The equilibrium stops
D.
The equilibrium constant becomes zero
Correct Answer:
The equilibrium shifts toward the products
Explanation:
Increasing temperature favors the endothermic direction because the system absorbs the added heat. Therefore, the equilibrium shifts toward the products.
2. For an exothermic equilibrium reaction, what happens when the temperature is increased?
A.
The equilibrium shifts toward the products
B.
The equilibrium shifts toward the reactants
C.
The reaction becomes irreversible
D.
The equilibrium constant remains unchanged
Correct Answer:
The equilibrium shifts toward the reactants
Explanation:
Heat acts like a product in an exothermic reaction. Increasing temperature favors the reverse direction, so the equilibrium shifts toward the reactants.
3. Consider the equilibrium: N2(g) + 3H2(g) ⇌ 2NH3(g) + heat. What is the effect of increasing temperature?
A.
More ammonia is formed
B.
Less ammonia is formed
C.
The amount of nitrogen becomes zero
D.
The reaction stops immediately
Correct Answer:
Less ammonia is formed
Explanation:
The forward formation of ammonia is exothermic because heat is produced. Increasing temperature shifts the equilibrium in the reverse direction, reducing ammonia formation.
4. Consider the equilibrium: CaCO3(s) ⇌ CaO(s) + CO2(g); ΔH > 0. What happens when the temperature is increased?
A.
The equilibrium shifts to the left
B.
The equilibrium shifts to the right
C.
The equilibrium remains permanently frozen
D.
The equilibrium constant becomes zero
Correct Answer:
The equilibrium shifts to the right
Explanation:
Since ΔH is positive, the forward reaction is endothermic. Increasing temperature favors the forward reaction, shifting equilibrium toward calcium oxide and carbon dioxide.
5. For an endothermic equilibrium, how does increasing temperature generally affect the equilibrium constant?
A.
It increases the equilibrium constant
B.
It decreases the equilibrium constant
C.
It always makes the equilibrium constant equal to one
D.
It has no effect on the equilibrium constant
Correct Answer:
It increases the equilibrium constant
Explanation:
For an endothermic reaction, increasing temperature favors product formation. Therefore, the equilibrium constant generally increases.
6. For an exothermic equilibrium, how does increasing temperature generally affect the equilibrium constant?
A.
It increases the equilibrium constant
B.
It decreases the equilibrium constant
C.
It makes the equilibrium constant infinite
D.
It changes the equilibrium constant to zero in every case
Correct Answer:
It decreases the equilibrium constant
Explanation:
For an exothermic reaction, increasing temperature favors the reverse reaction. Therefore, the equilibrium constant for the forward reaction generally decreases.
7. In the equilibrium H2(g) + I2(g) ⇌ 2HI(g), the forward reaction is endothermic. What happens to the amount of HI when temperature is increased?
A.
The amount of HI increases
B.
The amount of HI decreases
C.
The amount of HI becomes zero
D.
The amount of HI cannot change at equilibrium
Correct Answer:
The amount of HI increases
Explanation:
Because the forward reaction is endothermic, increasing temperature favors the forward direction. Thus, more hydrogen iodide is formed.
8. Which statement correctly describes the effect of lowering the temperature on an exothermic equilibrium reaction?
A.
It favors the products
B.
It favors the reactants
C.
It prevents equilibrium from being reached
D.
It always makes the reaction faster in both directions
Correct Answer:
It favors the products
Explanation:
In an exothermic reaction, heat is produced. Lowering the temperature favors the direction that produces heat, so the equilibrium shifts toward the products.
9. Which type of reaction is favored when the temperature of an equilibrium mixture is lowered?
A.
The endothermic reaction
B.
The exothermic reaction
C.
Neither reaction
D.
Only a reaction involving a catalyst
Correct Answer:
The exothermic reaction
Explanation:
Lowering temperature favors the direction that releases heat. Therefore, the exothermic reaction is favored.
10. At equilibrium, what is the main effect of increasing temperature on a chemical system?
A.
It favors the direction that absorbs heat
B.
It always favors the reactants
C.
It always favors the products
D.
It has no effect on the equilibrium position
Correct Answer:
It favors the direction that absorbs heat
Explanation:
According to the temperature effect on equilibrium, increasing temperature favors the endothermic direction, which absorbs the added heat.
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Effect of Temperature
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