 A simple cubic (primitive) unit cell has particles only at:
AThe 8 corners
BThe body centre
CThe corners and body centre
DThe 6 face centres
Answer & Solution
Correct answer: A. The 8 corners
A simple cubic unit cell has atoms only at its 8 corners. Each corner atom contributes $1/8$ to the unit cell (shared with 8 neighbouring cells), so the effective atoms per unit cell is $8 \times 1/8 = 1$.
Body-centred (option D) adds one atom at the centre, giving 2 atoms per cell. Face-centred (option C) adds atoms at the 6 face centres, each contributing $1/2$, giving 4 atoms per cell.
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