Potassium has a bcc structure with nearest neighour distance `4.52 Å`its atomic weight is `39` its density (in kg `m^(-3)`) will be

Options

A. 454
B. 804
C. 852
D. 908

Answer

D

Explanation

For bcc, `d = sqrt(3)/a`
or `a = (2d)/sqrt(3) = (2 xx 4.52)/1.732 = 5.219 A = 522 pm`
`rho = (Z xx M)/(a^(3) xx N_(0) xx 10^(-30)) = (2 xx 39)/((522)^(3) xx (6.022 xx 10^(23)) xx 10^(-30))`
`=0.91 g//cm^(3) = 910 kg m^(-3)`