What is the mass of an fcc unit cell if mass of one atom of an element is $6 \times 10^{-23} \mathrm{~g}$ ?
What is the mass of an fcc unit cell if mass of one atom of an element is $6 \times 10^{-23} \mathrm{~g}$ ?
$24 \times 10^{-22} \mathrm{~g}$
$4 \times 10^{-23} \mathrm{~g}$
$2 \cdot 4 \times 10^{-22} \mathrm{~g}$
$2 \cdot 4 \times 10^{-23} \mathrm{~g}$
Solution
In FCC, No. of atoms per unit cell $=4$
$\begin{aligned}
\text { Mass of unit cell } &=\text { Mass of } 4 \text { atoms }=4 \times 6 \times 10^{-23} \mathrm{~g} \\
&=24 \times 10^{-23} \mathrm{~g}=2.4 \times 10^{-22} \mathrm{~g}
\end{aligned}$