`X_(2)` is a greenish yellow gas with pungent offensive smell used in purification of water. It partially dissolves in `H_(2)O` to give a solution which turns blue litmus red. When `X_(2)` is passed through NaBr solution, `Br_(2)` is obtained.
What happens when `X_(2)` reacts with hot and conc. NaOH ? Give equation.

Explanation

To solve the problem, we need to identify the compound \( X_2 \) and then determine the products formed when it reacts with hot and concentrated sodium hydroxide (NaOH).

### Step-by-Step Solution:

1. **Identify \( X_2 \)**:
- The description states that \( X_2 \) is a greenish-yellow gas with a pungent smell, used in the purification of water, and partially dissolves in water to give a solution that turns blue litmus red.
- This indicates that \( X_2 \) is chlorine gas (\( Cl_2 \)). Chlorine is known for its use in water purification and has a strong, distinctive smell.

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