Question

Which of the following will have a metal deficiency defect?

• A. $\mathrm{FeO}$
• B. $\mathrm{ZnO}$
• C. $\mathrm{KCl}$
• D. $\mathrm{NaCl}$

Answer 1

The correct option is A

$\mathrm{FeO}$

Explanation of the correct option:

(A) $\mathrm{FeO}$

• The metal deficiency defect is caused due to missing cations.
• It means cationic vacancies, not anionic vacancies.
• The compounds $\mathrm{FeO}$ exhibit variable valances and they have the ability to take extra positive charges.
• In $\mathrm{FeO}$ crystals some ${\mathrm{Fe}}^{+2}$ ions are missing, so this loss of ions is made up by turning some ${\mathrm{Fe}}^{+2}$ to ${\mathrm{Fe}}^{+3}$ ions.

Explanation of incorrect options:

(B) $\mathrm{ZnO}$

• In the compound $\mathrm{ZnO}$, cationic vacancies do not occur, so $\mathrm{ZnO}$ will not have a metal deficiency defect.

(C) $\mathrm{KCl}$

• In the compound $\mathrm{KCl}$, cationic vacancies do not occur, so $\mathrm{KCl}$ will not have a metal deficiency defect.

(D) $\mathrm{NaCl}$

• In the compound $\mathrm{NaCl}$, cationic vacancies do not occur, so $\mathrm{NaCl}$ will not have a metal deficiency defect.

Hence, option (A) is correct., $\mathrm{FeO}$ has a metal deficiency defect.