Stoichiometric defects are also called ........................ .

$NaCl$ is heated in an atmosphere of sodium vapour. The resultant yellow colour is due to the formation of

What is non-stoichiometric defect? State its types.

Given below are two statements.
Statement $I:$ Frenkel defects are vacancy as well as interstitial defects.
Statement $II:$ Frenkel defect leads to colour in ionic solids due to presence of $F$-centres.
Choose the most appropriate answer for the statements from the options given below:

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

Which one of the following compounds shows both,Frenkel as well as Schottky defects?