Which of the chloride shows least solubility in water?

Options

A. KCl
B. NaCl
C. LiCl
D. CsCl

Answer

To determine which chloride shows the least solubility in water, we will analyze the solubility of chlorides of alkali metals (Group 1 elements). The chlorides we will consider are those of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

### Step-by-Step Solution:

1. **Identify the Group**: The question pertains to the chlorides of alkali metals, which are located in Group 1 of the periodic table. The elements in this group are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

2. **Understand Solubility Trends**: In general, the solubility of alkali metal chlorides in water tends to vary with the size of the cation. As we move down the group from lithium to cesium, the size of the cation increases.

3. **Cation Size and Charge Density**: The size of the cation affects its charge density. Lithium (Li+) is the smallest cation, while cesium (Cs+) is the largest. Smaller cations have higher charge density, which allows them to interact more effectively with water molecules.

4. **Effect on Solubility**: The solubility of a salt in water is influenced by the attraction between the cation and the anion, as well as the interaction with water molecules. Smaller cations (like Li+) can attract water molecules more effectively due to their higher charge density, leading to greater solubility.

5. **Conclusion**: As we move down the group, the increasing size of the cations (from Li+ to Cs+) leads to a decrease in solubility. Therefore, cesium chloride (CsCl), which has the largest cation, will show the least solubility in water compared to the other alkali metal chlorides.

### Final Answer:
The chloride that shows the least solubility in water is **cesium chloride (CsCl)**.

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