Which is (are) correct among the following ? .

Options

A. The radius of `CI^(Θ)` ion is `1.56 Å` while that of `Na^(o+)` ion is `0.95Å` .
B. The radius of `CI` atom is `0.99` while that of Na atom is `1.54`
C. The radius of `CI` atom is `0.99` while that of `CI^( Θ)` ion is `0.81`
D. The radius of Na atom is 0.95 while that of `Na^(o+)` ion is `1.54` .

Explanation

To determine which statements are correct regarding the ionic radii of Cl⁻ and Na⁺, we will analyze the properties of these ions based on their atomic structure and periodic trends.

### Step-by-Step Solution:

1. **Identify the Parent Atoms**:
- Sodium (Na) is in Group 1 (alkali metals) and has a parent atom of Na.
- Chlorine (Cl) is in Group 17 (halogens) and has a parent atom of Cl.

2. **Understand the Ionic Forms**:
- Sodium forms a cation (Na⁺) by losing one electron.
- Chlorine forms an anion (Cl⁻) by gaining one electron.

3. **Analyze the Size of Ions**:
- **Cations**: The size of cations is always smaller than their parent atoms because the loss of an electron leads to a higher effective nuclear charge (more protons than electrons), pulling the remaining electrons closer to the nucleus. Thus, Na⁺ will be smaller than Na.
- **Anions**: The size of anions is always larger than their parent atoms because the gain of an electron results in increased electron-electron repulsion and a lower effective nuclear charge (more electrons than protons). Thus, Cl⁻ will be larger than Cl.

4. **Compare the Sizes of Na⁺ and Cl⁻**:
- Since Na⁺ is smaller than Na and Cl⁻ is larger than Cl, we can compare the sizes of Na⁺ and Cl⁻ directly.
- Generally, within the same period, the size of cations decreases and the size of anions increases. Therefore, Na⁺ (a cation) will be smaller than Cl⁻ (an anion).

5. **Check the Given Options**:
- **Option 1**: Radius of Cl⁻ > Radius of Na⁺ (Correct)
- **Option 2**: Radius of Cl > Radius of Na (Incorrect, as Cl is larger than Na)
- **Option 3**: Radius of Cl⁻ > Radius of Cl (Incorrect, as Cl⁻ is larger than Cl)
- **Option 4**: Radius of Na > Radius of Na⁺ (Incorrect, as Na⁺ is smaller than Na)

6. **Conclusion**:
- The only correct statement is that the radius of Cl⁻ is greater than that of Na⁺.

### Summary of Correctness:
- The correct statement is that the radius of Cl⁻ is greater than the radius of Na⁺.