Question

An element with atomic mass 100 has a $bcc$ structure and edge length 400 pm. The density of element is:

• A. 10.37 g $c{m}^{-3}$
• B. 5.19 g $c{m}^{-3}$
• C. 7.29 g $c{m}^{-3}$
• D. 2.14 g $c{m}^{-3}$

Answer 1

The correct option is B 5.19 g $c{m}^{-3}$

Theoretical density of crystal, $\rho =\frac{nM}{N_o{a}^3}g/c{m}^3$

Given for bcc $n=2;a=400\times {10}^{-10}cm,M=100g$

$\therefore \rho =\frac{2\times 100}{6.022\times {10}^{23}\times (400{)}^3\times ({10}^{-10}{)}^3}$

$=5.19g/c{m}^3$

Hence, Option "B" is the correct answer.