Which of the following metal reacts with cold `H_(2)O` with the evolution of `H_(2)` gas?

Options

A. `Ca`
B. `Al`
C. `Zn`
D. `Cu`

Explanation

To determine which of the following metals reacts with cold water to produce hydrogen gas (H₂), we can analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the Metals**: The question provides a list of metals. Let's assume the options are:
- A) Calcium (Ca)
- B) Aluminum (Al)
- C) Zinc (Zn)
- D) Copper (Cu)

2. **Evaluate Calcium (Ca)**:
- Calcium is an alkaline earth metal.
- It reacts with cold water according to the equation:
\[ \text{Ca} + 2 \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{H}_2 \]
- This reaction produces calcium hydroxide and hydrogen gas. Therefore, calcium does react with cold water and evolves H₂ gas.

3. **Evaluate Aluminum (Al)**:
- Aluminum does not react with cold water due to the protective oxide layer that forms on its surface.
- It can react with steam to produce aluminum oxide and hydrogen, but not with cold water.

4. **Evaluate Zinc (Zn)**:
- Zinc also does not react with cold water.
- Like aluminum, it can react with steam to form zinc oxide and hydrogen gas but does not react with cold water.

5. **Evaluate Copper (Cu)**:
- Copper is a less reactive metal and does not react with cold water at all.
- It is known for its stability and does not produce hydrogen gas when in contact with cold water.

6. **Conclusion**:
- Among the metals listed, only calcium (Ca) reacts with cold water to produce hydrogen gas.

### Final Answer:
The metal that reacts with cold water with the evolution of hydrogen gas is **Calcium (Ca)**.