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

Options

A. NaCI
B. LiF
C. `Li_(2)CO_(3)`
D. `Na_(2)CO_(3)`

Explanation

To determine which of the given compounds are not soluble in water, we need to analyze each compound based on their solubility rules.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are NaCl, LiF, Li2CO3, and Na2CO3.

2. **Check Solubility of NaCl**:
- NaCl (sodium chloride) is an ionic compound.
- Ionic compounds that contain alkali metals (like sodium) are generally soluble in water.
- **Conclusion**: NaCl is soluble in water.

3. **Check Solubility of LiF**:
- LiF (lithium fluoride) is also an ionic compound.
- However, lithium ions (Li+) are small and have a high charge density, which allows them to polarize the fluoride ion (F-).
- This strong interaction makes LiF less soluble in water compared to other alkali metal fluorides.
- **Conclusion**: LiF is not soluble in water.

4. **Check Solubility of Li2CO3**:
- Li2CO3 (lithium carbonate) is another ionic compound.
- Similar to LiF, the small size of Li+ ions leads to strong interactions with the carbonate ion (CO3^2-), making it less soluble in water.
- **Conclusion**: Li2CO3 is not soluble in water.

5. **Check Solubility of Na2CO3**:
- Na2CO3 (sodium carbonate) is also an ionic compound.
- Sodium carbonate is soluble in water as it dissociates into sodium ions (Na+) and carbonate ions (CO3^2-).
- **Conclusion**: Na2CO3 is soluble in water.

### Final Answer:
The compounds that are **not soluble in water** are:
- **LiF**
- **Li2CO3**