# KCl crystallizes in the same type of lattice as does $NaCl$.Given that,$\large\frac{r_{Na^+}}{r_{Cl^-}}=$$0.5,\large\frac{r_{Na^+}}{r_{K^+}}=$$0.7$.Calculate the ratio of the side of the unit cell for KCl to that for NaCl and the ratio of density of NaCl to that for KCl.
$\begin{array}{1 1}1.143,1.172\\2.143,3.172\\3.143,0.172\\0.143,0.172\end{array}$