Question

Match the types of defects given in Column I with the statement given in Column II.

$\begin{array}{cccc}& columnl& & Columnll\\ \left(A\right)& Impuritydefect& \left(i\right)& NaclwithanionicsitescalledF-centres\\ \left(B\right)& Metalexcessdefect& \left(ii\right)& FeOwithf{e}^{3+}\\ \left(C\right)& Metaldeficiencydefect& \left(iii\right)& NaClwithS{r}^{2+}andsomecationicsitesvacant\end{array}$

Answer 1

Option (A)

The defects introduced in the crystal lattice due to the presence of a certain impurity are called impurity defects. This type of defect arises in the crystal due to the presence of impurity or a foreign particle in a lattice. When $S{r}^{2+}$replaces $2N{a}^{+}$ ions, it occupies only one site and leaves the other site vacant. Thus, this causes a vacancy.

Hence,
(A) → (iii)

$\begin{array}{ccc}\left(A\right)& Impuritydefect& \left(iii\right)NaClwithS{r}^{2+}andsomecationicsitesvacant\end{array}$

Option (B)

Metal excess defects can occur due to a missing anion from an ideal ionic solid, which leads to the creation of an F-centre, which is generally occupied by an unpaired electron. e.g., $NaCl$ with the anionic site.

Hence,
(B) → (i)

$\begin{array}{cccc}\left(B\right)& Metalexcessdefect& \left(i\right)& NaclwithanionicsitescalledF-centres\end{array}$

Option (C)

Metal deficiency defect occurs in $FeO$ because $F{e}^{2+}$ exists along with $F{e}^{3+}$ in $FeO$, which leads to an overall decrease in the number of metal ions. Three $F{e}^{2+}$ ions are replaced by two $F{e}^{3+}$ ions, thus maintaining electrical neutrality.

Hence, (C) → (ii)

$\begin{array}{cccc}\left(C\right)& Metaldeficiencydefect& \left(i\right)& FeOwithf{e}^{3+}\end{array}$