Which is most basic in character

Options

A. CsOH
B. KOH
C. NaOH
D. LiOH

Explanation

To determine which compound is the most basic in character among the alkali metal hydroxides, we will analyze the basicity of the hydroxides of alkali metals. The compounds we will consider are Sodium Hydroxide (NaOH), Potassium Hydroxide (KOH), Rubidium Hydroxide (RbOH), and Cesium Hydroxide (CsOH).

### Step-by-Step Solution:

1. **Understand Basicity**: Basicity is the ability of a compound to donate hydroxide ions (OH⁻) in solution. The stronger the base, the more readily it donates OH⁻ ions.

2. **Identify the Hydroxides**: We will examine the hydroxides of the alkali metals:
- Sodium Hydroxide (NaOH)
- Potassium Hydroxide (KOH)
- Rubidium Hydroxide (RbOH)
- Cesium Hydroxide (CsOH)

3. **Trends in Basicity**: The basicity of alkali metal hydroxides increases as we move down the group in the periodic table. This is due to the following reasons:
- The size of the metal ion increases from Na⁺ to Cs⁺.
- As the size of the metal ion increases, the bond between the metal ion and the hydroxide ion (OH⁻) becomes weaker.
- Weaker bonds result in a greater tendency for the hydroxide to dissociate and release OH⁻ ions.

4. **Comparison of Hydroxides**:
- NaOH: Basicity is moderate.
- KOH: Basicity is higher than NaOH.
- RbOH: Basicity is higher than KOH.
- CsOH: Basicity is the highest among these hydroxides.

5. **Conclusion**: Based on the trend of increasing basicity down the group, Cesium Hydroxide (CsOH) is the most basic in character among the given options.

### Final Answer:
**Cesium Hydroxide (CsOH) is the most basic in character.**