Which one of the following is correct order of increase of size?

Options

A. `Mg lt Na^(+) lt F^(-) lt Al`
B. `Na^(+) lt Al lt Mg lt F^(-)`
C. `Na^(+) lt F^(-) lt Al lt Mg`
D. `Na^(+) lt F^(-) lt Mg lt Al`

Explanation

To determine the correct order of increase of size among the given species (Na+, F-, Al, and Na), we need to analyze the ionic and atomic sizes based on their electronic configurations and positions in the periodic table.

### Step-by-Step Solution:

1. **Identify the Species**: The species given are Na+, F-, Al, and Na.

2. **Determine Isoelectronic Species**:
- Na+ and F- are isoelectronic, meaning they have the same number of electrons (10 electrons).
- The electronic configuration for both is 1s² 2s² 2p⁶.

3. **Compare Sizes of Isoelectronic Species**:
- In isoelectronic species, the size of the anion (F-) is larger than that of the cation (Na+). This is because the cation has a higher positive charge, which pulls the electrons closer to the nucleus, resulting in a smaller size.
- Therefore, the order between Na+ and F- is: F- > Na+.

4. **Compare Al and Mg**:
- Aluminium (Al) and Magnesium (Mg) are not isoelectronic, but we can compare their sizes based on their positions in the periodic table.
- Al has a higher nuclear charge than Mg, which results in a stronger attraction of the electrons to the nucleus, making Al smaller than Mg.
- Therefore, the order is: Mg > Al.

5. **Combine the Findings**:
- Now we combine the findings:
- From the isoelectronic comparison: F- > Na+
- From the periodic trend: Mg > Al
- Thus, we can arrange them in order of increasing size:
- Na+ < Al < Mg < F-

6. **Final Order**:
- The correct order of increasing size is: Na+ < Al < Mg < F-.

### Conclusion:
The correct order of increase of size is Na+ < Al < Mg < F-.