A : For exothermic reaction,
`DeltaH=E_a` (forward) `-E_a` (backward)
R : The value of activation energy for forward direction is less than activation energy for backward reaction.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion , then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion , then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements , then mark (4)

Answer

To solve the question, we need to analyze the assertion and reason provided regarding exothermic reactions and their activation energies.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that for an exothermic reaction, the change in enthalpy (ΔH) is equal to the activation energy (E_a) of the forward reaction minus the activation energy of the backward reaction.
- Mathematically, this can be expressed as:
\[ \Delta H = E_a (\text{forward}) - E_a (\text{backward}) \]

2. **Analyzing the Nature of Exothermic Reactions**:
- In exothermic reactions, the products have lower energy than the reactants, which means that the enthalpy change (ΔH) is negative.
- Therefore, we can conclude that:
\[ \Delta H < 0 \implies E_a (\text{forward}) < E_a (\text{backward}) \]

3. **Understanding the Reason**:
- The reason states that the activation energy for the forward direction is less than the activation energy for the backward reaction.
- This aligns with our conclusion from the assertion that for exothermic reactions, the activation energy for the backward reaction is indeed greater than that for the forward reaction.

4. **Conclusion**:
- Both the assertion and the reason are correct.
- The reason correctly explains the assertion because the relationship between ΔH and the activation energies is consistent with the nature of exothermic reactions.

### Final Answer:
Both the assertion (A) and reason (R) are correct, and R is the correct explanation of A.

---