Which of the following compounds is likely to show both Frenkel and Schottky defects in its crystalline form?

$A$ metallic solid undergoes Frenkel defect. Its original mass,volume and density are $M_0$,$V_0$ and $D_0$ respectively. After Frenkel defect the mass,volume and density are $M$,$V$ and $D$ respectively. The variations of $M$,$V$ and $D$ after Frenkel defect are

Explain the defects arising due to anionic vacancies and due to the presence of extra cations in the interstitial sites.

Which type of defect is observed in $AgBr$?

Schottky defect in a crystal is observed when,

When $NaCl$ (molten) is doped with $10^{-5} \, mol \, \%$ of $AlCl_3$,what is the concentration of cation vacancies?