Among the following which will have the lowest melting point and the highest solubility `LiCI,BeCI_(2),BCI_(3),C CI_(4)` .

Options

A. `C CI_(4),LiCI`
B. `LIiCI,C CI_(4)`
C. `BeCI_(2),BCI_(3)`
D. `BCI_(3),BeCI_(2)`

Explanation

To determine which compound among LiCl, BeCl₂, BCl₃, and CCl₄ has the lowest melting point and the highest solubility, we can analyze the ionic and covalent character of each compound based on Fajan's rules.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four compounds to analyze: LiCl, BeCl₂, BCl₃, and CCl₄.

2. **Determine the Cation Charges**:
- LiCl: Li⁺ (charge +1)
- BeCl₂: Be²⁺ (charge +2)
- BCl₃: B³⁺ (charge +3)
- CCl₄: C⁴⁺ (charge +4)

3. **Analyze Polarizing Power**:
- According to Fajan's rules, the polarizing power of a cation increases with its charge and decreases with its size.
- Therefore, as the charge increases from Li⁺ to C⁴⁺, the polarizing power also increases.

4. **Determine the Anion**:
- All compounds have the same anion, Cl⁻, which means we only need to focus on the cations for polarizing power.

5. **Assess Covalent Character**:
- The more polarizing the cation, the more covalent character the compound will have.
- Thus, CCl₄ will have the highest covalent character due to the +4 charge on carbon, while LiCl will have the least covalent character due to the +1 charge on lithium.

6. **Relate Covalent Character to Melting Point**:
- Compounds with higher covalent character generally have lower melting points because they have weaker intermolecular forces compared to ionic compounds.
- Therefore, CCl₄, with the highest covalent character, will have the lowest melting point.

7. **Relate Ionic Character to Solubility**:
- Compounds with more ionic character tend to be more soluble in polar solvents like water.
- Since LiCl has the least covalent character and the most ionic character, it will be the most soluble in water.

### Conclusion:
- **Lowest Melting Point**: CCl₄
- **Highest Solubility**: LiCl

Thus, the answer is:
- **Lowest Melting Point**: CCl₄
- **Highest Solubility**: LiCl