Which one of the following alkali metals gives hydrated salts?

Options

A. `Li`
B. `Na`
C. `K`
D. `Cs`

Explanation

To determine which alkali metal gives hydrated salts, we need to analyze the concept of charge density and its relationship with hydration.

### Step-by-Step Solution:

1. **Understanding Hydrated Salts**: Hydrated salts are salts that contain water molecules within their crystal structure. The ability of a metal ion to form hydrated salts is influenced by its charge density.

2. **Defining Charge Density**: Charge density is defined as the ratio of charge to the size of the ion. Mathematically, it can be expressed as:
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