Potassium is --------, ----------- and --------- than sodium.

Options

A. lighter, softer and more reactive
B. heavier, softer and less reactive
C. lighter, harder and more reactive
D. None of the above.

Explanation

To answer the question "Potassium is --------, ----------- and --------- than sodium," we will analyze the three properties of potassium in comparison to sodium: density, softness, and reactivity.

### Step-by-Step Solution:

1. **Density Comparison**:
- Potassium has a higher atomic volume compared to sodium.
- Because of this higher atomic volume, the density of potassium is less than that of sodium.
- Therefore, we can conclude that potassium is **lighter** than sodium.

2. **Softness Comparison**:
- As we move down the group in the periodic table, the softness of alkali metals increases.
- This is due to the decrease in ionization enthalpy, which weakens the metallic bonding in the lattice structure.
- Hence, potassium is **softer** than sodium.

3. **Reactivity Comparison**:
- Reactivity in alkali metals increases as we move down the group because the ionization enthalpy decreases.
- Since potassium has a lower ionization enthalpy compared to sodium, it is **more reactive** than sodium.

### Final Answer:
Potassium is **lighter**, **softer**, and **more reactive** than sodium.