Density of a unit cell is same as the density of the substance. If the density of the substance is known, number of atoms or dimensions of the unit cell can be calculated . The density of the unit cell is related to its mass(M), no. of atoms per unit cell (Z), edge length (a in cm) and Avogadro number N_A as :
`rho = (Z xx M)/(a^3 xx N_A)`
The number of atoms present in hte 100 g of a bcc crystal `(density=12.5 gcm^-3)` having cell edge 200 pm is

Options

A. `2.40 gcm^-3`
B. `40gcm^-3`
C. `4 g cm^-3`
D. `24 gcm^-3`