Which of the following lattices has the highest packing efficency (a) simple cubic, (b) body-centred cubic, and (c ) hexagonal close-packed lattice?

Explanation

To determine which of the given lattices has the highest packing efficiency, we need to analyze the packing efficiency of each type of lattice structure: simple cubic, body-centered cubic (BCC), and hexagonal close-packed (HCP).

### Step-by-Step Solution:

1. **Understanding Packing Efficiency**:
- Packing efficiency is defined as the fraction of the volume of a unit cell that is occupied by the constituent particles (atoms, ions, or molecules).
- It is calculated using the formula:
\[
...