Assertion: Formation of `Cl^(-)` ion is exothermic wheres `O^(2-)` ion formation is endothermic.
Reason: `EA_(2)` of oxygen is endothermic and greater than its exothermic `EA_(1)` value of oxygen.

Options

A. If both assertion and reason are true annd the reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but the reason is false
D. if assertion is false but the reason is true

Answer

To solve the problem, we need to analyze the assertion and the reason provided in the question regarding the formation of ions and their electron affinity.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the formation of the `Cl^(-)` ion is exothermic, while the formation of the `O^(2-)` ion is endothermic.
- Exothermic processes release energy (negative ΔH), while endothermic processes absorb energy (positive ΔH).

2. **Formation of `Cl^(-)` Ion**:
- Chlorine (Cl) has a high electron affinity, meaning it readily gains an electron to form `Cl^(-)`.
- The process can be represented as:
\[ \text{Cl} + e^- \rightarrow \text{Cl}^- \]
- This reaction releases energy, indicating that it is exothermic. Therefore, the assertion is correct for chlorine.

3. **Formation of `O^(2-)` Ion**:
- Oxygen (O) can gain two electrons to form `O^(2-)`. The process occurs in two steps:
1. The first step is the formation of `O^(-)`:
\[ \text{O} + e^- \rightarrow \text{O}^- \]
This step is exothermic as energy is released.
2. The second step involves adding another electron to form `O^(2-)`:
\[ \text{O}^- + e^- \rightarrow \text{O}^{2-} \]
This step is endothermic because the added electron experiences repulsion from the already present electrons, requiring energy input to overcome this repulsion.

4. **Understanding the Reason**:
- The reason states that the second electron affinity (`EA_2`) of oxygen is endothermic and greater than the first electron affinity (`EA_1`).
- This is true because the first electron affinity (`EA_1`) is exothermic (energy is released), while the second electron affinity (`EA_2`) is endothermic (energy is required).

5. **Conclusion**:
- Both the assertion and the reason are true. The formation of `Cl^(-)` is indeed exothermic, and the formation of `O^(2-)` is endothermic due to the nature of electron repulsion and energy requirements in the second electron affinity.

### Final Answer:
Both the assertion and the reason are true.