Which of the following metal reacts vigorously with cold water?

Options

A. zinc
B. iron
C. aluminium
D. sodium

Answer

To determine which metal reacts vigorously with cold water, we will analyze each option provided: zinc, iron, aluminum, and sodium.

### Step-by-Step Solution:

1. **Analyze Zinc (Zn)**:
- Atomic Number: 30
- Electronic Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s²
- Zinc belongs to the D block. The two electrons in the outermost shell (4s²) are not readily available for donation. Therefore, zinc does not react vigorously with cold water.

2. **Analyze Iron (Fe)**:
- Atomic Number: 26
- Electronic Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
- Iron also belongs to the D block. The last electrons enter the d-subshell, and the removal of these electrons requires energy. Thus, iron does not react vigorously with cold water.

3. **Analyze Aluminum (Al)**:
- Atomic Number: 13
- Electronic Configuration: 1s² 2s² 2p⁶ 3s² 3p¹
- Aluminum has three electrons in its outermost shell (3s² 3p¹). While it can react with water, it does not do so vigorously due to the energy required to remove these three electrons.

4. **Analyze Sodium (Na)**:
- Atomic Number: 11
- Electronic Configuration: 1s² 2s² 2p⁶ 3s¹
- Sodium is in the S block. It has one electron in its outermost shell (3s¹). Losing this single electron requires less energy, allowing sodium to react vigorously with cold water.

### Conclusion:
Among the metals analyzed, **sodium** is the one that reacts vigorously with cold water.

### Final Answer:
**Sodium** reacts vigorously with cold water.

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