The following is the correct increasing order of the ionic radii

Options

A. `Li^(+) lt Mg^(2+) lt K^(+) lt Al^(3+)`
B. `Al^(3+) lt Li^(+) lt Mg^(2+) lt K^(+)`
C. `Al^(3+) lt Mg^(2+) lt K^(+) lt Li^(+)`
D. `K^(+) lt Al^(3+) lt Mg^(2+) lt Li^(+)`

Explanation

To determine the correct increasing order of ionic radii for the ions given (Li⁺, Mg²⁺, K⁺, and Al³⁺), we can follow these steps:

### Step 1: Identify the Ions and Their Charges
The ions we are comparing are:
- Li⁺ (Lithium ion)
- Mg²⁺ (Magnesium ion)
- K⁺ (Potassium ion)
- Al³⁺ (Aluminum ion)

### Step 2: Understand the Concept of Ionic Radii
Ionic radii refer to the size of an ion. The size of an ion can be influenced by its charge and the number of electron shells. Cations (positively charged ions) are generally smaller than their parent atoms because they lose electrons, which reduces electron-electron repulsion and allows the remaining electrons to be pulled closer to the nucleus.

### Step 3: Analyze the Ions Based on Their Charges and Electron Shells
1. **K⁺ (Potassium ion)**:
- Has the largest ionic radius because it has the most electron shells (4 shells).

2. **Mg²⁺ (Magnesium ion)**:
- Has 3 shells and a +2 charge, making it smaller than K⁺ but larger than Li⁺ and Al³⁺.

3. **Al³⁺ (Aluminum ion)**:
- Has 3 shells but a +3 charge, which pulls the remaining electrons closer to the nucleus, making it smaller than Mg²⁺.

4. **Li⁺ (Lithium ion)**:
- Has the smallest ionic radius with only 2 shells and a +1 charge.

### Step 4: Establish the Order of Ionic Radii
Based on the analysis, we can establish the increasing order of ionic radii:
- Al³⁺ < Li⁺ < Mg²⁺ < K⁺

Thus, the correct increasing order of ionic radii is:
**Al³⁺ < Li⁺ < Mg²⁺ < K⁺**

### Final Answer
The correct increasing order of the ionic radii is:
**Al³⁺ < Li⁺ < Mg²⁺ < K⁺**

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