Assertion (A): `Li^(o+)` (aq) has large ionic redius than `Na^(o+)` (aq).
Reason (R ): `Li^(o+)` (aq) is relatively more hydrated as compared to
`Na^(o+)` aq.

Options

A. If both (A) and (R ) are correct and (R ) is the correct
explanation of (A).
B. If both (A) and (R ) are correct, but (R ) is not the correct
explanation of (A).
C. If (A) is correct, but (R ) is incorrect.
D. If (A) is incorrect, but (R ) is correct.

Answer

To solve the assertion and reason question regarding the ionic radius of `Li^(o+)` and `Na^(o+)`, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
The assertion states that `Li^(o+)` (aq) has a larger ionic radius than `Na^(o+)` (aq).

- **Understanding Ionic Radius**: The ionic radius is influenced by the charge density of the ion. Charge density is defined as the charge of the ion divided by its size (radius).
- **Comparison of `Li^(o+)` and `Na^(o+)`**: Lithium ion (`Li^(o+)`) has a smaller atomic size compared to sodium ion (`Na^(o+)`). However, because `Li^(o+)` has a higher positive charge (due to its smaller size), it has a higher charge density.

### Step 2: Conclusion on Assertion
- Since `Li^(o+)` has a higher charge density, it attracts water molecules more strongly, leading to a greater degree of hydration. This means that the hydrated radius of `Li^(o+)` can be larger than that of `Na^(o+)`.
- Thus, the assertion is **correct**.

### Step 3: Analyze the Reason
The reason states that `Li^(o+)` (aq) is relatively more hydrated compared to `Na^(o+)` (aq).

- **Hydration and Charge Density**: The degree of hydration is directly related to the charge density of the ion. Higher charge density leads to stronger attraction of water molecules.
- Since `Li^(o+)` has a higher charge density than `Na^(o+)`, it will indeed be more hydrated.

### Step 4: Conclusion on Reason
- The reason provided is also **correct** and explains why the assertion is true.

### Final Conclusion
Both the assertion and reason are correct, and the reason correctly explains the assertion. Therefore, the correct option for this question is **Option A**.

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