When $SrCl_2$ is added to molten $NaCl$ and crystallized,the defect formed is ........

Schottky defect in a crystal is observed when,

If $NaCl$ is doped with $10^{-5} \ mol$ of $AlCl_3$,what will be the concentration of cation vacancies?

Which of the following solids does not exhibit Frenkel defect?

$A$ 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

If $NaCl$ is doped with $10^{-3} \, mol \% \, SrCl_2$,what will be the concentration of cation vacancies?