Assertion (A) : In a reversible endothermic reaction, `E_("act")` of the forward reaction is higher than that of the backward reaction
Reason (R) : The threshold energy of the forward reaction is more than that of the backward reaction.

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true

Answer

To solve the assertion and reason question, we will analyze both statements step-by-step.

### Step 1: Understanding the Assertion (A)
**Assertion (A):** In a reversible endothermic reaction, the activation energy (E_act) of the forward reaction is higher than that of the backward reaction.

- In an endothermic reaction, the reactants absorb heat to form products. This means that the energy of the products is higher than that of the reactants.
- The activation energy for the forward reaction is the energy required to convert reactants into an activated complex, which then forms products.
- Since the products are at a higher energy level than the reactants, the energy barrier (activation energy) for the forward reaction must be higher than that for the backward reaction (which is the conversion of products back to reactants).

**Conclusion for Assertion (A):** True.

### Step 2: Understanding the Reason (R)
**Reason (R):** The threshold energy of the forward reaction is more than that of the backward reaction.

- The threshold energy refers to the minimum energy required for the reactants to reach the activated complex.
- In a reversible reaction, the threshold energy for both the forward and backward reactions is determined by the internal energies of the reactants and products, along with their respective activation energies.
- In an endothermic reaction, the internal energy of the products is greater than that of the reactants. However, the threshold energy (which includes activation energy) is not necessarily greater for the forward reaction than for the backward reaction. In fact, the threshold energy is the same for both directions because it is based on the energy levels of the reactants and products.

**Conclusion for Reason (R):** False.

### Final Conclusion
- Assertion (A) is true.
- Reason (R) is false.

Thus, the correct answer is that Assertion (A) is true, and Reason (R) is false.

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