What does the structure of a solid containing a Schottky defect possess?

Explain how vacancies are introduced in an ionic solid when a cation of higher valence is added as an impurity in it.

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 .....

Which type of defect is observed in crystals like $NaCl$ and $KCl$?

If a trivalent atom replaces a few silicon atoms in the three-dimensional network of silicon dioxide,what would be the type of charge on the overall structure?

Which of the following statements is $WRONG$?