Which is more basic in character?

Options

A. `NaOH`
B. `KOH`
C. `RbOH`
D. `LiOH`

Answer

To determine which hydroxide is more basic among the given options (NaOH, KOH, RbOH, and LiOH), we need to consider the basicity of alkali metal hydroxides.

### Step-by-Step Solution:

1. **Understanding Basicity**: Basicity refers to the ability of a substance to accept protons (H⁺ ions) or donate hydroxide ions (OH⁻). In the case of alkali metal hydroxides, their basicity is influenced by the metal ion present.

2. **Group Trends**: Alkali metals are found in Group 1 of the periodic table. As we move down the group from lithium (Li) to rubidium (Rb), the size of the metal ion increases. This affects the hydroxide's ability to dissociate in water.

3. **Dissociation of Hydroxides**: When alkali metal hydroxides dissolve in water, they dissociate into their respective metal ions and hydroxide ions:
- NaOH → Na⁺ + OH⁻
- KOH → K⁺ + OH⁻
- RbOH → Rb⁺ + OH⁻
- LiOH → Li⁺ + OH⁻

4. **Comparing Basicity**: The basicity of these hydroxides increases as the size of the metal ion increases. This is due to the lower lattice energy of the hydroxides formed by larger alkali metals, which makes it easier for them to dissociate and release OH⁻ ions into the solution.

5. **Conclusion**: Among the given options:
- LiOH (lithium hydroxide) is the least basic.
- NaOH (sodium hydroxide) is more basic than LiOH.
- KOH (potassium hydroxide) is more basic than NaOH.
- RbOH (rubidium hydroxide) is the most basic of all.

Thus, the most basic hydroxide among the given options is RbOH (rubidium hydroxide).

### Final Answer:
**RbOH (rubidium hydroxide) is the most basic in character.**