When a catalyst is introduced into a reversible reaction

Options

A. Increases rate of forward reaction only
B. Increases rate of backward reaction only
C. Equilibrium is not changed
D. Attains equilibrium quickly

Explanation

### Step-by-Step Solution:

1. **Understanding Reversible Reactions**:
- A reversible reaction is one where the products can react to form the original reactants. This means that the reaction can proceed in both the forward and backward directions.

2. **Role of Activation Energy**:
- For any reaction to occur, it must overcome a certain amount of energy known as activation energy. This is the energy required to reach the transition state from the reactants.

3. **Introducing a Catalyst**:
- A catalyst is a substance that increases the rate of a reaction without being consumed in the process. It achieves this by lowering the activation energy needed for the reaction to proceed.

4. **Effect of Catalyst on Activation Energy**:
- When a catalyst is introduced into a reversible reaction, it lowers the activation energy for both the forward and backward reactions. This means that both the forward reaction (reactants to products) and the backward reaction (products to reactants) can occur more easily.

5. **Impact on Reaction Rates**:
- With the activation energy lowered, the rates of both the forward and backward reactions increase. Importantly, they increase at equal rates.

6. **Achieving Equilibrium**:
- Since the rates of the forward and backward reactions increase equally, the system reaches equilibrium more quickly. At equilibrium, the rate of the forward reaction equals the rate of the backward reaction.

7. **Conclusion**:
- Therefore, the introduction of a catalyst into a reversible reaction does not change the position of equilibrium but allows the system to reach equilibrium faster.

### Final Answer:
When a catalyst is introduced into a reversible reaction, it speeds up both the forward and backward reactions equally, allowing the system to attain equilibrium more quickly.

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