`Ca(OH)_(2)` removes temporary hardness by forming

Options

A. (A) `CaCl_(2)`
B. (B) `CaSO_(4)`
C. (C) `CaCO_(3)`
D. (D) `MgCO_(3)`

Answer

To solve the question regarding how calcium hydroxide \((Ca(OH)_2)\) removes temporary hardness, we can break it down into several steps:

### Step-by-Step Solution:

1. **Understanding Temporary Hardness**:
- Temporary hardness in water is primarily caused by the presence of bicarbonates of calcium and magnesium, specifically calcium bicarbonate \((Ca(HCO_3)_2)\) and magnesium bicarbonate \((Mg(HCO_3)_2)\).

2. **Role of Calcium Hydroxide**:
- Calcium hydroxide \((Ca(OH)_2)\) is used to treat water with temporary hardness. When added to water, it reacts with the bicarbonates present.

3. **Chemical Reactions**:
- When calcium bicarbonate is heated or reacts with calcium hydroxide, it decomposes to form calcium carbonate \((CaCO_3)\) and water:
\[ Ca(HCO_3)_2 \rightarrow CaCO_3 + H_2O \]
- Similarly, magnesium bicarbonate reacts with calcium hydroxide to form magnesium carbonate \((MgCO_3)\) and water:
\[ Mg(HCO_3)_2 \rightarrow MgCO_3 + H_2O \]

4. **Formation of Insoluble Compounds**:
- Both calcium carbonate and magnesium carbonate are insoluble in water. Therefore, they precipitate out of the solution, effectively removing the hardness from the water.

5. **Conclusion**:
- Thus, calcium hydroxide removes temporary hardness by forming insoluble calcium carbonate and magnesium carbonate.

### Final Answer:
Calcium hydroxide \((Ca(OH)_2)\) removes temporary hardness by forming calcium carbonate \((CaCO_3)\) and magnesium carbonate \((MgCO_3)\).

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