A diatomic molecule ${\mathrm{X}}_2$ has a body-centred cubic $\left(\mathrm{bcc}\right)$ structure with a cell edge of $300 \mathrm{pm}.$ The density of the molecule is $6.17 {\mathrm{gcm}}^{-3}.$ The number of molecules present in $200 \mathrm{g}$ of ${\mathrm{X}}_2$ is :
(Avogadro constant $\left({\mathrm{N}}_{\mathrm{A}}\right)=6\times {10}^{23}{\mathrm{mol}}^{-1}$)