Explain the following term with a suitable example:
$(ii)$ Frenkel defect

Assertion : No compound has both Schottky and Frenkel defects.
Reason : Both defects change the density of the solid.

$A$ sample of ferrous oxide has actual formula $Fe_{0.93}O_{1.00}$. In this sample,what fraction of metal ions are $Fe^{2+}$ ions? What type of non-stoichiometric defect is present in this sample?

When $Fe_{0.93}O$ is heated in the presence of oxygen,it converts to $Fe_2O_3$. The number of correct statement$(s)$ from the following is:
$A.$ The equivalent weight of $Fe_{0.93}O$ is $\frac{\text{Molecular weight}}{0.79}$.
$B.$ The number of moles of $Fe^{2+}$ and $Fe^{3+}$ in $1 \text{ mole}$ of $Fe_{0.93}O$ is $0.79$ and $0.14$ respectively.
$C.$ $Fe_{0.93}O$ is metal deficient with a lattice comprising of a cubic closed-packed arrangement of $O^{2-}$ ions.
$D.$ The $\%$ composition of $Fe^{2+}$ and $Fe^{3+}$ in $Fe_{0.93}O$ is $85\%$ and $15\%$ respectively.

Write a short note on Frenkel defect and Schottky defect.

Which type of crystal defect is observed in the diagram given below?
$Na^{+} Cl^{-} Na^{+} Cl^{-} Na^{+} Cl^{-}$
$Cl^{-} \square Cl^{-} Na^{+} \square Na^{+}$
$Na^{+} Cl^{-} \square Cl^{-} Na^{+} Cl^{-}$
$Cl^{-} Na^{+} Cl^{-} Na^{+} \square Na^{+}$