Question

Lithium has a bcc structure .Its density is `530 kg m^(-3)` and its atomic mass is `6.94 g mol^(-1)` .Calculate the edge length of a unit cell of lithium metal `(N_(A) = 6.02 xx 10^(23) mol^(-1))`
A. `264` pm
B. `154` pm
C. `352` pm
D. `527` pm

Answer 1

Correct Answer - d
`d = (ZM)/(N_(A) xx a^(3))` , for `BC C Z = 2`
`530 kg//m^(3) = (2 xx 6.94 xx 10^(-3))/(6.02 xx 10^(23) xx a^(3))`
`a^(3) = 43.50 xx 10^(-30)`
`a= 3.52 xx 10^(-10) m = 352` pm