Calcium crystallizes in f.c.c unit cell with 0.556 nm. Calculate the density if it contain 0.1% Schottky detects

$$\begin{gathered} \mathrm{In} \mathrm{schotty} \mathrm{defect}, {\mathrm{Z}}_{\mathrm{eff}} \mathrm{changes}. \mathrm{So}, \mathrm{density} \mathrm{also} \mathrm{changes}. \\ {\mathrm{Z}}_{\mathrm{new}}=4-\frac{4\times 0.1}{100}=3.996 \\ \mathrm{\rho }=\frac{\mathrm{Z}\times {\mathrm{M}}_{\mathrm{A}}}{{\mathrm{N}}_{\mathrm{A}}\times {\mathrm{a}}^3} \\ \Rightarrow \mathrm{\rho }=\frac{3.996\times 40}{6.023\times {10}^{23}\times 171.8\times {10}^{-24}} \\ \Rightarrow \mathrm{\rho }\approx 1.547 \mathrm{gm}/\mathrm{c}.\mathrm{c} \end{gathered}$$