Out of the following metals which will give `H_(2)` on reaction with `NaOH:`
`I: Zn,` ,`II:Mg`,
`III: Al,`,`IV:Be`

Options

A. I, II, III, IV
B. I, III, IV
C. II, IV
D. I, III

Explanation

To determine which of the given metals will produce hydrogen gas (H₂) when reacted with sodium hydroxide (NaOH), we will analyze the reactions of each metal with NaOH.

### Step-by-Step Solution:

1. **Identify the Metals**: The metals given are:
- I: Zinc (Zn)
- II: Magnesium (Mg)
- III: Aluminium (Al)
- IV: Beryllium (Be)

2. **Reaction of Zinc with NaOH**:
- The reaction can be represented as:
\[ \text{Zn} + 2 \text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2 \]
- **Conclusion**: Zinc reacts with NaOH to produce hydrogen gas.

3. **Reaction of Magnesium with NaOH**:
- The reaction can be represented as:
\[ \text{Mg} + 2 \text{NaOH} \rightarrow \text{Mg(OH)}_2 + \text{H}_2 \]
- However, magnesium typically forms a protective oxide layer that prevents it from reacting immediately with NaOH. Therefore, it does not release hydrogen gas under normal conditions.
- **Conclusion**: Magnesium does not produce hydrogen gas when reacted with NaOH.

4. **Reaction of Aluminium with NaOH**:
- The reaction can be represented as:
\[ 2 \text{Al} + 2 \text{NaOH} + 6 \text{H}_2\text{O} \rightarrow 2 \text{NaAl(OH)}_4 + 3 \text{H}_2 \]
- **Conclusion**: Aluminium reacts with NaOH to produce hydrogen gas.

5. **Reaction of Beryllium with NaOH**:
- The reaction can be represented as:
\[ \text{Be} + 2 \text{NaOH} + 2 \text{H}_2\text{O} \rightarrow \text{Na}_2\text{Be(OH)}_4 + \text{H}_2 \]
- **Conclusion**: Beryllium also reacts with NaOH to produce hydrogen gas.

### Final Conclusion:
The metals that will produce hydrogen gas when reacted with NaOH are:
- I: Zinc (Zn)
- III: Aluminium (Al)
- IV: Beryllium (Be)

Thus, the answer is **I, III, and IV**.

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