Which of the following is in the increasing order of the ionic character

Options

A. `PbCl_(4) lt PbCl_(2) lt CaCl_2 lt NaCl`
B. `PbCl_(2) lt PbCl_(4) lt CaCl_(2) lt NaCl`
C. `PbCl_(2) lt PbCl_(4) lt NaCl lt CaCl_(2)`
D. `PbCl_(4) lt PbCl_(2) lt NaCl lt CaCl_(2)`

Explanation

To determine the increasing order of ionic character among the given compounds (PbCl4, PbCl2, CaCl2, and NaCl), we can follow these steps:

### Step 1: Understand Ionic Character
Ionic character refers to the extent to which a compound exhibits ionic bonding as opposed to covalent bonding. The higher the ionic character, the more the compound behaves like an ionic compound.

### Step 2: Analyze the Compounds
We have the following compounds to analyze:
1. PbCl4 (Lead(IV) chloride)
2. PbCl2 (Lead(II) chloride)
3. CaCl2 (Calcium chloride)
4. NaCl (Sodium chloride)

### Step 3: Apply Fajans' Rules
Fajans' rules help us determine the ionic character based on the size of the cation and anion:
- A smaller cation and a larger anion lead to a higher ionic character.
- A larger cation and a smaller anion lead to a higher covalent character.

### Step 4: Compare PbCl4 and PbCl2
- **PbCl4** has lead in the +4 oxidation state, which results in a smaller cation size compared to **PbCl2**, where lead is in the +2 oxidation state.
- Since PbCl4 has a smaller cation, it has more covalent character than PbCl2, which means PbCl2 has a higher ionic character than PbCl4.

### Step 5: Compare CaCl2 and NaCl
- **CaCl2** has a +2 charge on calcium, while **NaCl** has a +1 charge on sodium.
- The lattice energy (and thus ionic character) is greater for compounds with higher charges. Therefore, CaCl2 will have a higher ionic character than NaCl.

### Step 6: Establish the Order
Based on the analysis:
- PbCl4 has the least ionic character.
- PbCl2 has a higher ionic character than PbCl4.
- CaCl2 has a higher ionic character than both PbCl2 and PbCl4.
- NaCl has a higher ionic character than CaCl2.

### Final Order
The increasing order of ionic character is:
**PbCl4 < PbCl2 < CaCl2 < NaCl**