In alkaline medium, which elements can produce hydrogen?

Options

A. Zn, Si
B. Cu, Ag
C. Cu, `N_(2)`
D. Al, C

Answer

To determine which elements can produce hydrogen in an alkaline medium, we will analyze the reactions of various elements with sodium hydroxide (NaOH).

**Step-by-Step Solution:**

1. **Identify the elements to be tested**: We will consider zinc, silicon, copper, aluminum, and carbon.

2. **Test Zinc (Zn)**:
- Reaction: \( \text{Zn} + 2 \text{NaOH} \rightarrow \text{Na}_2\text{ZnO} + \text{H}_2 \)
- Conclusion: Zinc reacts with sodium hydroxide to produce hydrogen gas (H2).

3. **Test Silicon (Si)**:
- Reaction: \( \text{Si} + 4 \text{NaOH} \rightarrow \text{Na}_4\text{SiO}_4 + 2 \text{H}_2 \)
- Conclusion: Silicon also reacts with sodium hydroxide to produce hydrogen gas (H2).

4. **Test Copper (Cu)**:
- Reaction: \( \text{Cu} + 2 \text{NaOH} \rightarrow \text{Cu(OH)}_2 + \text{Na}_2\text{O} \)
- Conclusion: Copper does not produce hydrogen when reacted with sodium hydroxide.

5. **Test Aluminum (Al)**:
- Reaction: \( 2 \text{Al} + 6 \text{NaOH} \rightarrow 2 \text{Na}_3\text{AlO}_3 + 3 \text{H}_2 \)
- Conclusion: Aluminum reacts with sodium hydroxide to produce hydrogen gas (H2).

6. **Test Carbon (C)**:
- Reaction: Carbon does not react with sodium hydroxide to produce hydrogen.
- Conclusion: Carbon does not produce hydrogen in alkaline medium.

7. **Final Analysis**:
- From the tests, we conclude that zinc, silicon, and aluminum can produce hydrogen in an alkaline medium. Copper and carbon do not produce hydrogen.

**Final Answer**: The elements that can produce hydrogen in alkaline medium are **Zinc (Zn)**, **Silicon (Si)**, and **Aluminum (Al)**.

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