Question

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
A. `454`
B. `804`
C. `852`
D. `910`

Answer 1

Correct Answer - d
For bcc , `d= sqrt(3)/(2)a`
`a= (2d)/(sqrt(3)) = (2xx 52)/(1.732) = 5.219 Å= 522 "pm"`
`rho = (Z xx 39)/(a^(3) N_(0) 10^(-30))`
`= (2 xx 59)/((522)^(3) xx (6.023 xx 10^(23)) xx 10^(-30))`
`= 0.91 g//m^(3) = 910 kg m^(-1)`