In which one of the following reactions `H_(2)` is liberated?

Options

A. `NaH+H_(2)O to`
B. `NaCl+H_(2)O to`
C. `Na_(2)O+H_(2)O to `
D. `NaOH+H_(2)O to `

Answer

To determine in which reaction hydrogen gas (H₂) is liberated, we will analyze the given options step by step.

### Step 1: Analyze the Reactions
We need to look at each reaction provided in the options to see if hydrogen gas is produced.

### Step 2: Examine Option A
**Reaction: Sodium Hydride (NaH) + Water (H₂O)**
- When sodium hydride reacts with water, it produces sodium hydroxide (NaOH) and hydrogen gas (H₂).
- The balanced equation is:
\[ \text{NaH} + \text{H}_2\text{O} \rightarrow \text{NaOH} + \text{H}_2 \]
- **Conclusion**: Hydrogen gas is liberated in this reaction.

### Step 3: Examine Option B
**Reaction: Sodium Chloride (NaCl) + Water (H₂O)**
- Sodium chloride does not react with water to produce hydrogen gas. Instead, it dissociates into sodium ions (Na⁺) and chloride ions (Cl⁻).
- There is no production of H₂ in this reaction.

### Step 4: Examine Option C
**Reaction: Sodium Oxide (Na₂O) + Water (H₂O)**
- When sodium oxide reacts with water, it forms sodium hydroxide (NaOH).
- The balanced equation is:
\[ \text{Na}_2\text{O} + \text{H}_2\text{O} \rightarrow 2 \text{NaOH} \]
- **Conclusion**: No hydrogen gas is liberated in this reaction.

### Step 5: Examine Option D
**Reaction: Sodium Hydroxide (NaOH) + Water (H₂O)**
- Sodium hydroxide does not react with water to produce hydrogen gas. Instead, it simply dissolves in water.
- **Conclusion**: No hydrogen gas is liberated in this reaction.

### Final Conclusion
From the analysis, the only reaction that liberates hydrogen gas is:
- **Option A: Sodium Hydride (NaH) + Water (H₂O)**

Thus, the correct answer is **Option A**.

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