which one of the following statements is correct? In a reversible reaction a catalyst

Options

A. Increases the rate of forward reaction
B. Decreases the rate of forward reaction
C. Increases the rate of backward and forward reactions
D. Alters the equilibrium constant of the reactin

Explanation

To solve the question regarding the role of a catalyst in a reversible reaction, we can break it down into the following steps:

### 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 both the forward reaction (A → B) and the backward reaction (B → A) can occur.

2. **Role of a Catalyst**:
- A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It achieves this by providing an alternative pathway for the reaction with a lower activation energy.

3. **Effect of a Catalyst on Reaction Rates**:
- In a reversible reaction, a catalyst will increase the rate of both the forward and backward reactions equally. This means that it does not favor one direction over the other; instead, it accelerates both processes.

4. **Equilibrium Considerations**:
- While a catalyst speeds up the attainment of equilibrium, it does not change the position of the equilibrium or the equilibrium constant (K). The equilibrium constant is determined by the nature of the reactants and products and their concentrations at equilibrium, not by the presence of a catalyst.

5. **Evaluating the Options**:
- Based on the above understanding, we can evaluate the given options:
- **Option 1**: Increases the rate of the forward reaction. (Partially true, but incomplete)
- **Option 2**: Decreases the rate of the forward reaction. (False)
- **Option 3**: Increases the rate of the backward and forward reactions. (True)
- **Option 4**: Does not affect the equilibrium constant. (True but does not fully address the catalyst's role)

6. **Conclusion**:
- The correct statement regarding the role of a catalyst in a reversible reaction is that it increases the rate of both the forward and backward reactions, thus allowing the system to reach equilibrium faster without affecting the equilibrium constant.

### Final Answer:
**Option 3: Increases the rate of the backward and forward reactions.**

---