Which of the following has been arranged order of increasing covalent character ? .

Options

A. `KCI lt CaCI_(2) lt AICI_(3) lt SnCI_(4)`
B. `SnCI_(4) lt AICI_(3) lt CaCI_(2) lt KCI`
C. `AICI_(3) lt CaCI_(2) lt KCI lt SnCI_(4)`
D. `CaCI_(2) lt SnCI_(4) lt KCI lt AICI_(3)`

Explanation

To determine the order of increasing covalent character among the given compounds (KCl, CaCl2, AlCl3, and SnCl4), we will apply Fajans' rules, which help us understand how the size and charge of cations influence their covalent character.

### Step-by-Step Solution:

1. **Understand Fajans' Rules**:
- Fajans' rules state that the covalent character of an ionic compound increases with:
- Decreasing size of the cation.
- Increasing charge on the cation.

2. **Identify the Cations**:
- For KCl, the cation is K⁺.
- For CaCl2, the cation is Ca²⁺.
- For AlCl3, the cation is Al³⁺.
- For SnCl4, the cation is Sn⁴⁺.

3. **Analyze the Size and Charge of Cations**:
- K⁺ has a +1 charge.
- Ca²⁺ has a +2 charge.
- Al³⁺ has a +3 charge.
- Sn⁴⁺ has a +4 charge.
- As the charge on the cation increases, the covalent character also increases.

4. **Rank the Cations by Charge**:
- The order of cations based on increasing charge is:
- K⁺ (1+)
- Ca²⁺ (2+)
- Al³⁺ (3+)
- Sn⁴⁺ (4+)

5. **Determine the Order of Increasing Covalent Character**:
- Since K⁺ has the lowest charge and Sn⁴⁺ has the highest charge, the order of increasing covalent character is:
- KCl < CaCl2 < AlCl3 < SnCl4

6. **Final Answer**:
- The correct order of increasing covalent character among the given compounds is KCl < CaCl2 < AlCl3 < SnCl4.