Out of `KCI` and `CaO`, which has higher lattice energy and why?

Explanation

To determine which compound, KCl or CaO, has higher lattice energy, we need to analyze the factors that influence lattice energy. Lattice energy is defined as the energy required to separate one mole of an ionic solid into its gaseous ions. It is influenced by the charges of the ions and the distance between them (which is related to their sizes).

### Step-by-Step Solution:

1. **Understanding Lattice Energy**:
Lattice energy is the energy released when gaseous ions combine to form an ionic solid. It is also the energy required to break an ionic solid into gaseous ions.

**Hint**: Remember that higher charges and smaller ionic sizes lead to stronger ionic bonds and thus higher lattice energy.
...