Among `LiCl, BeCl_2, BCl_3 and C Cl_4`, the covalent bond charater follows the order-

Options

A. `LiCl gt BeCl_2 gt BCl_3 gt C Cl_4`
B. `LiCl lt BeCl_2 lt BCl_3 lt C Cl_4`
C. `LiCl gt BeCl_2 gt C Cl_4 gt BCl_3`
D. `LiCl lt BeCl_2 lt BCl_3 gt C Cl_4`

Answer

To determine the order of covalent bond character among LiCl, BeCl₂, BCl₃, and CCl₄, we can apply Fajans' rules, which help us understand how ionic compounds can exhibit covalent character based on the size of cations and anions.

### Step-by-Step Solution:

1. **Understanding Fajans' Rules**:
- Fajans' rules state that the covalent character of an ionic bond increases with:
- Smaller size of the cation.
- Larger size of the anion.
- This is because a smaller cation has a higher charge density, which increases its polarizing power, while a larger anion is more easily polarized.

2. **Analyzing the Compounds**:
- **LiCl**:
- Cation: Li⁺ (small size)
- Anion: Cl⁻ (larger size)
- **BeCl₂**:
- Cation: Be²⁺ (smaller than Li⁺ due to higher charge)
- Anion: Cl⁻
- **BCl₃**:
- Cation: B³⁺ (even smaller due to higher charge)
- Anion: Cl⁻
- **CCl₄**:
- Cation: C⁴⁺ (smallest due to highest charge)
- Anion: Cl⁻

3. **Comparing Cation Sizes**:
- As we move from Li⁺ to Be²⁺ to B³⁺ to C⁴⁺, the size of the cation decreases due to increasing positive charge.
- This means that the polarizing power increases, leading to greater covalent character.

4. **Comparing Anion Sizes**:
- The anion (Cl⁻) remains the same in all cases. However, the charge on the cation is increasing, which enhances the covalent character.

5. **Determining the Order**:
- Based on the analysis:
- CCl₄ has the highest covalent character due to the smallest cation and highest charge.
- BCl₃ follows, as it has a smaller cation than BeCl₂.
- BeCl₂ comes next, as it has a smaller cation than LiCl.
- LiCl has the least covalent character due to the larger cation compared to the others.

### Final Order of Covalent Character:
CCl₄ > BCl₃ > BeCl₂ > LiCl