Calculate the number `(n)` of atoms contained within `(a)` cubic cell, `(b)` a body `-` centred cubic cell, `(c)` a face `-` centred cubic cell.

Explanation

`(a)` The cubic unit cell has 8 atoms at eight corners. Each atom is shared by 8 unit cells.
`:. Z=8xx(1)/(8)=1`
`(b)` The body `-` centred cubic cell consists of 8 atoms at the corners and one atom at centre.
`x=(8xx(1)/(8))+1=2`
`(c)` The face `-` centred cubic unit cell consists of 8 atoms at the eight corners and one atom at each of the six faces. This atom at the face is shared by two unit cells.
`z=(1)/(8)+(6xx(1)/(2))=4`