Caesium chloride may be considered to form interpenetrating simple primitive cubic crystals. The edge length of unit cell is $412\;pm$. Determine the density of $CsCl$

Question

$\begin{array}{1 1} 4.0\;g\;cm^{-3} \\ 7 \;g\;cm^{-3} \\ 8\;g\;cm^{-3} \\ 9\;g\;cm^{-3} \end{array} $