Which one of the following statements is not correct?

Options

A. Catalyst does not initial any reaction.
B. the value of equilibrium constant is changed in the pressure of a catalyst in the reaction at equilibrium.
C. Enzymes catalyse mainly bio - chemical reactions.
D. Coenzymes increase the catalytic activity of enzyme.

Answer

To determine which statement is not correct regarding chemical equilibrium and catalysts, let's analyze each option step by step:

### Step 1: Analyze Option 1
**Statement:** "A catalyst does not initiate any reaction."
- **Explanation:** A catalyst is a substance that increases the rate of a reaction without being consumed in the process. It does not initiate a reaction; it only speeds it up. Therefore, this statement is correct.

### Step 2: Analyze Option 2
**Statement:** "The value of the equilibrium constant is changed in the presence of a catalyst."
- **Explanation:** The equilibrium constant (K) is determined by the concentrations of reactants and products at equilibrium and is not affected by the presence of a catalyst. A catalyst speeds up the rate at which equilibrium is reached but does not change the position of equilibrium or the value of K. Therefore, this statement is incorrect.

### Step 3: Analyze Option 3
**Statement:** "Enzymes catalyze mainly biochemical reactions."
- **Explanation:** Enzymes are biological catalysts that facilitate biochemical reactions in living organisms. This statement is correct.

### Step 4: Analyze Option 4
**Statement:** "Coenzymes increase the catalytic activity of enzymes."
- **Explanation:** Coenzymes are non-protein molecules that assist enzymes in catalyzing reactions. They can enhance the activity of enzymes and help in the conversion of substrates into products. This statement is also correct.

### Conclusion
After analyzing all the statements, we find that:
- Option 1 is correct.
- Option 2 is incorrect (this is the answer we are looking for).
- Option 3 is correct.
- Option 4 is correct.

Thus, the statement that is not correct is **Option 2**: "The value of the equilibrium constant is changed in the presence of a catalyst."

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