Frenkel and Schottky defects are

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

How do defects arise in crystals? State the types of defects.

Use the appropriate symbols $T$ (True) or $F$ (False) for the following statements regarding defects in solids:
$(1)$ Frenkel defect arises due to the arrangement of cations and anions with a very small difference in size.
$(2)$ Frenkel defect can be called a dislocation defect.
$(3)$ $F$-centers arise due to the migration of electrons released from metal atoms into the crystal lattice.
$(4)$ Physical properties of the crystal do not change due to Schottky defect.

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

$A$ metal oxide shows $p-$type semiconductivity. The conductivity of the oxide will increase by: