Which of the following statements is not correct for the catalyst ?

Options

A. It catalyses the forward and backward reactions to the same extent
B. It alters `Delta`G for the reaction
C. It is a substance that does not change the equilibrium constant of a reaction
D. It provides an alternate mechanism by reducing activation energy between reactants and products.

Explanation

To determine which statement is not correct regarding catalysts, we can analyze each statement based on the properties and functions of catalysts in chemical reactions. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Role of Catalysts
A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy required for the reaction to occur. It does not undergo any permanent chemical change itself and can be recovered after the reaction.

### Step 2: Analyze Each Statement
1. **Statement 1**: "It catalyzes the forward and backward reaction to the same extent."
- **Analysis**: This statement is correct. Catalysts affect both the forward and reverse reactions equally by lowering the activation energy for both processes.

2. **Statement 2**: "It alters ΔG for the reaction."
- **Analysis**: This statement is incorrect. A catalyst does not change the Gibbs free energy change (ΔG) of a reaction. It only provides an alternative pathway with a lower activation energy. ΔG is determined by the difference in energy between reactants and products, which remains unchanged.

3. **Statement 3**: "It is a substance that does not change the equilibrium constant of a reaction."
- **Analysis**: This statement is correct. The equilibrium constant is dependent only on the temperature and not on the presence of a catalyst.

4. **Statement 4**: "It provides an alternate mechanism by reducing activation energy between the reactants and products."
- **Analysis**: This statement is also correct. Catalysts provide an alternative reaction pathway that has a lower activation energy.

### Step 3: Identify the Incorrect Statement
From the analysis, we see that the second statement is the only one that is not correct regarding catalysts.

### Conclusion
The statement that is not correct for the catalyst is: **"It alters ΔG for the reaction."**

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