Experimentally,it was found that a metal oxide has the formula $M_{0.98}O$. The metal $M$ is present as $M^{2+}$ and $M^{3+}$ in its oxide. The fraction of the metal which exists as $M^{3+}$ would be: .................... $\%$

In the Schottky defect,

Write a short note on non-stoichiometric defects.

The correct statement$(s)$ regarding defects in solids is(are):
$A$. Frenkel defect is usually favoured by a very small difference in the sizes of cation and anion.
$B$. Frenkel defect is a dislocation defect.
$C$. Trapping of an electron in the lattice leads to the formation of $F$-center.
$D$. Schottky defects have no effect on the physical properties of solids.

In $AgBr$ crystal,the ion size lies in the order $Ag^{+} << Br^{-}$. The $AgBr$ crystal should have the following characteristics:

In ionic compounds where the sizes of the cation and anion are almost similar,which defect is observed?