Which of the following is/are found in the solid state ?

Options

A. `LiHCO_(3)`
B. `KHCO_(3)`
C. `NaHCO_(3)`
D. `RbHCO_(3)`

Explanation

To determine which of the given bicarbonates of alkali metals are found in the solid state, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Substances**:
We need to identify the bicarbonates of alkali metals mentioned in the question. Common alkali metal bicarbonates include:
- Lithium bicarbonate (LiHCO3)
- Sodium bicarbonate (NaHCO3)
- Potassium bicarbonate (KHCO3)
- Rubidium bicarbonate (RbHCO3)

2. **Understand the Nature of Alkali Metal Bicarbonates**:
Alkali metal bicarbonates are generally basic in nature. This basicity contributes to their stability in the solid state.

3. **Analyze Each Bicarbonate**:
- **LiHCO3 (Lithium bicarbonate)**: This bicarbonate is an exception among alkali metal bicarbonates. Due to its small ionic size and diagonal relationship with magnesium bicarbonate (MgHCO3), it tends to exist in a solution form rather than solid.
- **NaHCO3 (Sodium bicarbonate)**: This bicarbonate is stable and exists in the solid state.
- **KHCO3 (Potassium bicarbonate)**: This bicarbonate is also stable and exists in the solid state.
- **RbHCO3 (Rubidium bicarbonate)**: Similar to sodium and potassium bicarbonates, rubidium bicarbonate is stable and exists in the solid state.

4. **Conclusion**:
Based on the analysis, the bicarbonates that are found in the solid state are:
- NaHCO3 (Sodium bicarbonate)
- KHCO3 (Potassium bicarbonate)
- RbHCO3 (Rubidium bicarbonate)

The only bicarbonate that does not exist in the solid state is LiHCO3 (Lithium bicarbonate).

### Final Answer:
The bicarbonates found in the solid state are:
- KHCO3 (Potassium bicarbonate)
- NaHCO3 (Sodium bicarbonate)
- RbHCO3 (Rubidium bicarbonate)