(i) Frenkel defect

(ii) Schottky defect

(iii) Vacancy defect

(iv) Metal deficiency defect

Correct Answer: (i) Frenkel defect

Explanation: Ionic solids that contain significant differences in ion sizes reflect this type of feature. When a small ion frequency cation is moved from its normal position to an internal structure, a Frenkel defect is formed. The Frenkel defect is also known as the dislocation defect.