Which among the following solids shows Frenkel defect?

Schottky defect is generally observed in which of the following?

Schottky defect defines imperfection in the lattice structure of a

Explain Schottky defect and Frenkel defect.

If $10^{-4} \, \text{mole} \%$ of $SrCl_2$ is added to $NaCl$,the concentration of cation vacancies created is...... $(N_A = 6.02 \times 10^{23} \, \text{mol}^{-1})$

Analysis of the density of an electrically neutral $NaCl$ crystal containing vacancies yielded the following results:
$(i)$ Density of $NaCl$ crystal with all sites occupied $= 2.178 \times 10^3 \ kg \ m^{-3}$
$(ii)$ Density of $NaCl$ crystal with vacancies $= 2.165 \times 10^3 \ kg \ m^{-3}$
Then the percentage of vacancies in the $NaCl$ crystal is .....