When electrons are trapped into the crystal in anion vacancy,the defect is known as

What is non-stoichiometric defect? State its types.

Explain stoichiometric defects shown by non-ionic solids.

The pyknometric density of sodium chloride crystal is $2.165 \times 10^3 \ kg \ m^{-3}$ while its $X$-ray density is $2.178 \times 10^3 \ kg \ m^{-3}$. The fraction of unoccupied sites in sodium chloride crystal is

Iron crystallizes in $FCC$ with an edge length of $400 \ pm$. If it contains $0.1 \%$ Schottky defects, calculate its approximate density $[AW \text{ of } Fe = 56 \ g/mol]$. (in $g/cm^3$)

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ In a particular point defect,an ionic solid is electrically neutral,even if few of its cations are missing from its unit cells.
Reason $(R):$ In an ionic solid,Frenkel defect arises due to dislocation of cation from its lattice site to interstitial site,maintaining overall electrical neutrality.
In the light of the above statements,choose the most appropriate answer from the options given below: