The edge length of a cubic unit cell of metallic calcium is 556 pm.If the density of calcium is $1.54gcm^{-3}$ and its molar mass is $40.08gmol^{-3}$.Calculate the radius of calcium atom.

Question

$\begin{array}{1 1}196.6pm\\186.6pm\\206.6pm\\176.6pm\end{array} $