$F$-centers are

When $KCl$ is heated in an atmosphere of $K$ vapor,it appears violet. This is because .................

The pyknometric density of sodium chloride crystal is $2.165 \times 10^3 \ kg \ m^{-3}$ while its $X$-ray density is $2.178 \times 10^3 \ kg \ m^{-3}$. The fraction of unoccupied sites in sodium chloride crystal is

Non-stoichiometric cuprous oxide,$Cu_{2}O$ can be prepared in the laboratory. In this oxide,the copper to oxygen ratio is slightly less than $2:1$. Can you account for the fact that this substance is a $p$-type semiconductor?

The correct statement regarding defects in crystalline solids is

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