Why equilibrium constant of a reaction does not change in the presence of a catalyst ?

Explanation

### Step-by-Step Solution:

1. **Understanding Equilibrium**:
At equilibrium, the rate of the forward reaction (reactants converting to products) is equal to the rate of the backward reaction (products converting back to reactants). This means that the concentrations of reactants and products remain constant over time.

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 lowering the activation energy required for the reaction to occur.

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