$CsBr$ crystallises in a body centered cubic lattice. The unit cell length is $436.6\; pm$ . Given that the atomic mass of $Cs = 133$ and of $Br = 80\; amu$. Avogadro's number being $6.02\times10^{23}mol^{-1}$ The density of $CsBr$ is

Question

$(a)\;8.50g/cm^3\qquad(b)\;4.25g/cm^3\qquad(c)\;42.5g/cm^3\qquad(d)\;0.425g/cm^3$