Point defects are present in

Missing of one monovalent cation and one monovalent anion from the crystal lattice is called

What type of crystal defect is indicated in the diagram below?
$Na^{+} \, Cl^{-} \, Na^{+} \, Cl^{-} \, Na^{+} \, Cl^{-}$
$Cl^{-} \, \Box \, Cl^{-} \, Na^{+} \, \Box \, Na^{+}$
$Na^{+} \, Cl^{-} \, \Box \, Cl^{-} \, Na^{+} \, Cl^{-}$
$Cl^{-} \, Na^{+} \, Cl^{-} \, Na^{+} \, \Box \, Na^{+}$

What kind of defects do most ionic crystals possess?

What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?

Schottky defect and Frenkel defect are ....... .