Question

The density of metal which crystallise in $bcc$ lattice with unit cell edge length $300$ pm and molar mass $50$ g mol${}^{-1}$ will be:

• A. $10$ g cm${}^{-3}$
• B. $14.2$ g cm${}^{-3}$
• C. $6.15$ g cm${}^{-3}$
• D. $9.31$ g cm${}^{-3}$

Answer 1

Answer: (C)

$6.15$ g cm${}^{-3}$

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

Given for bcc $n=2;a=300\times {10}^{-10}cm,M=50g$

$\therefore \rho =\frac{2\times 50}{6.022\times {10}^{23}\times (300{)}^3\times ({10}^{-10}{)}^3}$

$=6.15g/c{m}^3$

Hence, Option "C" is the correct answer.