Which of the following compounds is/are not soluble in water?

Options

A. `Li_(2)CO_(3)`
B. `LiF`
C. `Li_(3)PO_(4)`
D. All of these

Explanation

To determine which of the given compounds are not soluble in water, we will analyze each compound based on the solubility rules for ionic compounds.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- Li2CO3 (Lithium Carbonate)
- LiF (Lithium Fluoride)
- Li3PO4 (Lithium Phosphate)

2. **Check Solubility of Each Compound**:
- **Li2CO3 (Lithium Carbonate)**:
- Generally, carbonates are not soluble in water except for those of alkali metals and ammonium. However, lithium carbonate has limited solubility due to the small size of Li+ ion, which can polarize the carbonate ion (CO3^2-), making it less soluble.
- **LiF (Lithium Fluoride)**:
- Fluorides of alkali metals are typically soluble in water, but lithium fluoride is an exception. The small Li+ ion forms strong ionic bonds with the F- ion, resulting in low solubility in water.
- **Li3PO4 (Lithium Phosphate)**:
- Phosphates are generally insoluble in water, but lithium phosphate is an exception as lithium salts of phosphates tend to be more soluble. However, due to the small size of Li+, it can also have limited solubility.

3. **Conclusion**:
- Based on the analysis, we find that:
- Li2CO3 is not very soluble.
- LiF is not soluble.
- Li3PO4 has limited solubility.
- Therefore, all three compounds can be considered as not soluble in water.

4. **Final Answer**: The correct option indicating compounds that are not soluble in water is **all of these**.