Question

A metal crystallises as body centred cubic lattice with the edge length of unit cell equal to $0.304$ nm. If the molar mass of the metal is $50.3$ g mol${}^{-1}$, its density (in g cm${}^{-3}$) is :

• A. $5.945$
• B. $2.9725$
• C. $8.9175$
• D. $4.458$

Answer 1

Answer: (A)

$5.945$

The expression for density is given below:

Z=2 for BCC, M= 50.3 g/ mol, $a=0.304nm=0.304\times {10}^{-7}cm$ and $N_A=6.0\times {10}^{23}$

$d=\frac{zM}{N_A{a}^3}$ $=\frac{2\times 50.3}{{6\times 10}^{23}\times {(0.304\times {10}^{-7})}^3}=5.945$ g cm${}^{-3}$

Option A is correct.