When zeolite which is hydrated sodium aluminium silicate, is treated with hard water the sodium ions are exchange with

Options

A. `H^(+)` ions
B. `Ca^(2+)` ions
C. `SO_(4)^(2-)`
D. `Mg^(2+)` ions

Explanation

To solve the question regarding the exchange of sodium ions in zeolite when treated with hard water, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Zeolite Composition**:
- Zeolite is a hydrated sodium-aluminium silicate, which can be represented as Na-Al-Si-O. The sodium ions (Na⁺) are part of its structure.

2. **Identifying Hard Water Components**:
- Hard water typically contains high concentrations of calcium ions (Ca²⁺) and magnesium ions (Mg²⁺). These ions are responsible for the hardness of water.

3. **Ion Exchange Process**:
- When zeolite comes into contact with hard water, a process called ion exchange occurs. The sodium ions in zeolite are exchanged with the calcium and magnesium ions present in hard water.

4. **Reaction Mechanism**:
- For example, when calcium ions (Ca²⁺) from hard water come into contact with zeolite, they can replace sodium ions (Na⁺) in the zeolite structure.
- The reaction can be represented as:
\[ \text{Na-Al-Si-O} + \text{Ca}^{2+} \rightarrow \text{Ca-Al-Si-O} + 2\text{Na}^{+} \]
- Here, one calcium ion replaces two sodium ions.

5. **Conclusion**:
- Therefore, when zeolite is treated with hard water, the sodium ions are exchanged with calcium ions (Ca²⁺).

6. **Final Answer**:
- The correct answer to the question is that sodium ions are exchanged with **Ca²⁺ ions**.