Question

A compound having bcc geometry has atomic mass $50$ amu. Calculate the density (in g cm${}^{-3}$) of the unit cell, if its edge length is $290$ pm.

• A. $6.81$
• B. $3.40$
• C. $13.62$
• D. None of the above

Answer 1

The correct option is A $6.81$

The expression for the density of the unit cell is given below.

$d=\frac{n\times M}{a^3\times N_A}$

Here, $M=50$

For bcc, $n=2$

$a=290$ pm $=290\times {10}^{-10}$ cm

Substituting values in the expression for density, we get

$d=\frac{2\times 50}{(290\times {10}^{-10}{)}^3\times 6.023\times {10}^{23}}=6.81$ g cm${}^{-3}$

Hence, the density of the unit cell is $6.81$ g cm${}^{-3}$.