The correct arrangement for the ions in the increasing order of their radii is

Options

A. `Na^(+), C1^(-) , Ca^(2+) `
B. `Ca^(2+) , K^(+) , S^(2-)`
C. `Na^(+) , A1^(3+) ,Be^(2+)`
D. `C1^(-) ,F^(-) , S^(2-)`

Explanation

To determine the correct arrangement of ions in increasing order of their radii, we need to consider the following steps:

### Step 1: Identify the Ions
List the ions that need to be compared. For example, let's say we have the following ions: Na⁺, Cl⁻, K⁺, and O²⁻.

### Step 2: Understand Ionic Radii Trends
- Cations (positively charged ions) are generally smaller than their parent atoms because they lose one or more electrons, resulting in a reduced electron-electron repulsion and a stronger attraction of the remaining electrons to the nucleus.
- Anions (negatively charged ions) are generally larger than their parent atoms because they gain one or more electrons, which increases electron-electron repulsion and decreases the effective nuclear charge on each electron.

### Step 3: Compare the Ions
- **Cations**: Among Na⁺ and K⁺, Na⁺ has a smaller radius because it has fewer electron shells than K⁺.
- **Anions**: Among Cl⁻ and O²⁻, O²⁻ has a larger radius than Cl⁻ because it has more electrons and increased electron-electron repulsion.

### Step 4: Arrange the Ions
Now that we understand the trends:
1. Na⁺ (smallest)
2. Cl⁻ (larger than Na⁺)
3. K⁺ (larger than Na⁺)
4. O²⁻ (largest)

### Step 5: Final Arrangement
The correct arrangement in increasing order of ionic radii is:
Na⁺ < Cl⁻ < K⁺ < O²⁻

### Summary
The final answer for the increasing order of ionic radii is:
**Na⁺ < Cl⁻ < K⁺ < O²⁻**

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