Which of the following solids does not exhibit Frenkel defect?

Give examples of displacement defects in solids.

Which of the following statements is $NOT$ true about Schottky defect?

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

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 .....

For $NaCl$,the number of Schottky pairs per $cm^3$ at room temperature is