Arrange the following in the increasing order of their
`NaCl, MgCl_(2), SiCl_(4), AlCl_(3)("ionic character")`

Answer

To arrange the compounds NaCl, MgCl₂, SiCl₄, and AlCl₃ in increasing order of their ionic character, we will use Fajan's rule, which helps us understand how the size and charge of cations affect their ability to polarize anions, thus influencing the ionic and covalent character of the compounds.

### Step-by-Step Solution:

1. **Identify the Cations**:
- NaCl contains Na⁺
- MgCl₂ contains Mg²⁺
- AlCl₃ contains Al³⁺
- SiCl₄ contains Si⁴⁺

2. **Understand Polarizing Power**:
- The polarizing power of a cation increases with its charge and decreases with its size. Smaller cations with higher charges can distort the electron cloud of anions more effectively, leading to increased covalent character and decreased ionic character.

3. **Compare Cation Sizes**:
- Na⁺ is the largest cation (1+ charge).
- Mg²⁺ is smaller than Na⁺ (2+ charge).
- Al³⁺ is smaller than Mg²⁺ (3+ charge).
- Si⁴⁺ is the smallest cation (4+ charge).

4. **Determine Polarization and Ionic Character**:
- Since Na⁺ is the largest, it has the least polarizing power and thus the highest ionic character.
- Mg²⁺ has more polarizing power than Na⁺, leading to a lower ionic character than NaCl.
- Al³⁺ has even higher polarizing power, resulting in a further decrease in ionic character.
- Si⁴⁺ has the highest polarizing power due to its small size and high charge, leading to the lowest ionic character among the four compounds.

5. **Order the Compounds**:
- Based on the analysis, we can arrange the compounds in increasing order of ionic character:
- SiCl₄ < AlCl₃ < MgCl₂ < NaCl

### Final Answer:
**Increasing order of ionic character**: SiCl₄ < AlCl₃ < MgCl₂ < NaCl