Due to $Frenkel$ defect,the density of ionic solids

Iron crystallizes in $FCC$ with an edge length of $400 \ pm$. If it contains $0.1 \%$ Schottky defects, calculate its approximate density $[AW \text{ of } Fe = 56 \ g/mol]$. (in $g/cm^3$)

If molten $NaCl$ contains $SrCl_2$ as impurity,crystallization can generate

Ionic solids,which have anionic vacancies due to metal excess defect,develop colour. Explain with the help of a suitable example.

Which among the following statements is $NOT$ true about Frenkel defect?

Which of the following solids does not exhibit Frenkel defect?