Question

`Na` and `Mg` crystallize in bcc- and fcc-type crystals, the ratio of number of atoms present in the unit cell of their respective crystal is
A. 4 and 2
B. 9 and 14
C. 14 and 9
D. 2 and 4

Answer 1

Correct Answer - D
In BCC (Na)
No. of atoms per unit cell `=8xx1//8+1=2`
In FCC. (Mg)
No. of atoms per unit cell `=8xx1//8+6xx1//2=4`
The number of atoms in unit cells are respectively 2 and 4