Question

Sodium crystallizes in bcc lattice of side length equal to $4.30\mathring{A}$. Atomic mass of $\text{Na}$ is $23$ amu. The number of atoms present in a unit lattice is:

• A. $2$
• B. $5$
• C. $8$
• D. $3$

Answer 1

The correct option is A $2$

In bcc structure,

the number of atoms at corners per unit cell

= $\frac{1}{8}\times 8=1=$ atom

the number of atoms at body centre per unit cell = 1 atom

$\therefore$ Total number of atoms per unit cell = 1 + 1 =2 atoms

Hence, the correct option is $\text{A}$