Question

Out of $NaCl$ and $AgCl$, which one shows Frenkel defect and why?

Answer 1

Frenkel defect:
It is that defect in which one smaller ion (usually cations) move from its lattice position to an interstitial site, i.e. a tetrahedral or octahedral hole to form a vacancy in the lattice.
$AgCl$ has the defect because the size difference between $A{g}^{+}$ and $C{l}^{-}$ is considerable so it can exhibit Frenkel defect. $NaCl$ does not exhibit this defect as both the ions have similar sizes.