Which of the following statements is correct about the defects in the crystals?

Options

A. Schottky defect is observed in the compounds in which there is a large difference in the size of cation and anion, whereas Frenkel defect is observed when cation and anion are approximately of the same size.
B. Schottky defects disturb the ratio of cations and anions, whereas Frenkel defects maintain the ratio.
C. Schottky defects lead to lowering in density, whereas Frenkel defects do not affect the density.
D. Both interstitial defect and Frenkel defect cause increase in the density of solid

Answer

C

Explanation

Schottky defect is observed in ionic solids in which cationic and anionic sizes are approximately the same. It arises when equal number of cations and anions are missing from their position. It causes decrease in the density of solid.
Frenkel defect is observed in ionic solids in which cationic and anionic size difference is large. it arises when the smaller ion leaves its original place and moves into iterstitial space. this causes no change in cation-anion ratio, and hence no change in the density. Interstitial defect arises when a constituting particle is also placed into interstitial space. this causes an increase in density.