The temporary hardness of water is caused by which of the following compound(s).

Options

A. `CaCl_2`
B. `Mg(HCO_3)_2`
C. `Ca(HCO_3)_2`
D. `MgSO_4`

Answer

To determine which compounds cause temporary hardness of water, we can analyze the options given:

1. **Calcium Chloride (CaCl₂)**: This compound does not cause temporary hardness. It is a soluble salt that contributes to permanent hardness because it does not precipitate out when water is boiled.

2. **Magnesium Hydrogen Bicarbonate (Mg(HCO₃)₂)**: This compound does cause temporary hardness. Magnesium hydrogen bicarbonate is soluble in water and can lead to temporary hardness, which can be removed by boiling.

3. **Calcium Hydrogen Bicarbonate (Ca(HCO₃)₂)**: This compound also causes temporary hardness. Like magnesium hydrogen bicarbonate, calcium hydrogen bicarbonate is soluble in water and contributes to temporary hardness, which can be removed by boiling.

4. **Magnesium Sulfate (MgSO₄)**: This compound does not cause temporary hardness. It contributes to permanent hardness because it remains in solution even after boiling.

Based on this analysis, the compounds that cause temporary hardness of water are **Magnesium Hydrogen Bicarbonate (Mg(HCO₃)₂)** and **Calcium Hydrogen Bicarbonate (Ca(HCO₃)₂)**.

### Final Answer:
The temporary hardness of water is caused by:
- Magnesium Hydrogen Bicarbonate (Mg(HCO₃)₂)
- Calcium Hydrogen Bicarbonate (Ca(HCO₃)₂)