What does the structure of a solid containing a Schottky defect possess?

$A$ 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?

Use the appropriate symbols $T$ (True) or $F$ (False) for the following statements regarding defects in solids:
$(1)$ Frenkel defect arises due to the arrangement of cations and anions with a very small difference in size.
$(2)$ Frenkel defect can be called a dislocation defect.
$(3)$ $F$-centers arise due to the migration of electrons released from metal atoms into the crystal lattice.
$(4)$ Physical properties of the crystal do not change due to Schottky defect.

At what temperature will the Schottky defect be maximum?

Assertion : Due to Frenkel defect,there is no effect on the density of the crystalline solid.
Reason : In Frenkel defect,no cation or anion leaves the crystal.

If $NaCl$ is doped with $10^{-3} \, mol \%$ of $SrCl_{2}$,what is the concentration of cation vacancies?