Which of the following change `(s)` in the presence of catalyst ? (More than one correct answer)

Options

A. Velocity coefficient of the reaction
B. `DeltaG^(ɵ)` of the reaction
C. Energy of activation
D. `Delta H` of the reaction

Explanation

To solve the question regarding which changes occur in the presence of a catalyst, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding the 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.

2. **Analyzing Each Option**:
- **Option A: Velocity Coefficient of the Reaction**:
- The velocity coefficient (or rate constant, k) of a reaction is influenced by the activation energy. Since a catalyst lowers the activation energy, it will increase the rate constant (k). Therefore, this option is correct.

- **Option B: ΔG of the Reaction**:
- The Gibbs free energy change (ΔG) of a reaction is determined by the difference in energy between the reactants and products, and it is not affected by the presence of a catalyst. Thus, this option is incorrect.

- **Option C: Energy of Activation**:
- The energy of activation (Ea) is the minimum energy required for a reaction to occur. A catalyst lowers the activation energy, making this option correct.

- **Option D: ΔH of the Reaction**:
- The change in enthalpy (ΔH) of a reaction is a state function and is determined by the difference in energy between the products and reactants. A catalyst does not change the enthalpy of the reaction, so this option is incorrect.

3. **Conclusion**:
- The changes that occur in the presence of a catalyst are:
- **Velocity Coefficient of the Reaction (Option A)**: Changes.
- **Energy of Activation (Option C)**: Changes.
- Therefore, the correct answers are **Option A and Option C**.

### Final Answer:
The changes that occur in the presence of a catalyst are:
- **Option A: Velocity Coefficient of the Reaction**
- **Option C: Energy of Activation**

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