Which of the following is strongly hydrated in aqueous solution ?

Options

A. (a) `Li^(o+)`
B. (b) `Na^(o+)`
C. (c) `K^(o+)`
D. (d) `Cs^(o+)`

Explanation

To determine which alkali metal ion is strongly hydrated in aqueous solution, we can follow these steps:

### Step 1: Understand Hydration
Hydration refers to the interaction of ions with water molecules. The extent of hydration is influenced by the charge density of the ion, which is the ratio of the charge of the ion to its size.

### Step 2: Identify Charge Density
Since all the ions in question (Li⁺, Na⁺, K⁺, Cs⁺) have the same charge (+1), we need to compare their sizes. The smaller the ion, the higher the charge density, which leads to stronger hydration.

### Step 3: Compare Sizes of Alkali Metal Ions
The sizes of the alkali metal ions increase as we move down the group in the periodic table:
- Li⁺ (Lithium ion) - smallest
- Na⁺ (Sodium ion)
- K⁺ (Potassium ion)
- Cs⁺ (Cesium ion) - largest

### Step 4: Determine Hydration Extent
Since Li⁺ is the smallest ion among the given options, it has the highest charge density. Therefore, it will be the most strongly hydrated ion in aqueous solution.

### Step 5: Conclusion
Based on the analysis, Li⁺ (Lithium ion) is the ion that is strongly hydrated in aqueous solution.

### Final Answer
Li⁺ is strongly hydrated in aqueous solution.

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