Which of the bicarbonate does not exist in solid state?

Options

A. `NaHCO_(3)`
B. `KHCO_(3)`
C. `Ca(HCO_(3))_(2)`
D. `RbHCO_(3)`

Answer

To determine which bicarbonate does not exist in solid state, we can analyze the properties of the bicarbonates of the given elements.

### Step-by-Step Solution:

1. **Identify the Bicarbonates**: We have four options:
- Option 1: Sodium bicarbonate (NaHCO₃)
- Option 2: Potassium bicarbonate (KHCO₃)
- Option 3: Calcium bicarbonate (Ca(HCO₃)₂)
- Option 4: Rubidium bicarbonate (RbHCO₃)

2. **Group Classification**:
- Sodium, potassium, and rubidium are alkali metals (Group 1).
- Calcium is an alkaline earth metal (Group 2).

3. **Stability of Bicarbonates**:
- Bicarbonates of alkali metals (sodium, potassium, rubidium) are stable and can exist in solid form at room temperature.
- Bicarbonates of alkaline earth metals (like calcium) are generally less stable and can decompose.

4. **Specific Behavior of Calcium Bicarbonate**:
- Calcium bicarbonate (Ca(HCO₃)₂) is not stable at room temperature. It tends to decompose and react with carbon dioxide (CO₂) in the atmosphere to form calcium carbonate (CaCO₃) and water (H₂O).
- This reaction indicates that calcium bicarbonate does not exist in solid form under normal conditions.

5. **Conclusion**:
- Since calcium bicarbonate is not stable at room temperature and does not exist in solid state, the answer is **Option 3: Calcium bicarbonate (Ca(HCO₃)₂)**.

### Final Answer:
**Calcium bicarbonate does not exist in solid state.**