Question: 73: Match List-I with List-II :
| List – I (Defects) | List – II (shown by) |
|---|---|
| (a) Frenkel defect | (i) non-ionic solids and density of the solid decreases |
| (b) Schottky defect | (ii) non-ionic solids and density of the solid increases |
| (c) Vacancy defect | (iii) ionic solids and density of the solid decreases |
| (d) Interstitial defect | (iv) ionic solids and density of the solid remains constant |
Choose the correct answer from the options given below :
(1) (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
(2) (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
(3) (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
(4) (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
Answer: Option (4)
Explanation:
Frenkel defect occurs in ionic solids when a smaller ion, usually a cation,
leaves its lattice position and occupies an interstitial site.
Since the total number of ions remains the same, the mass and volume do not change,
so the density remains constant. Hence, Frenkel defect corresponds to ionic solids with constant density, that is (a)-(iv).
Schottky defect is found in ionic solids when equal numbers of cations and
anions are missing from their lattice sites.
This reduces the mass of the solid while the volume remains almost the same, leading to a decrease in density.
Therefore, Schottky defect corresponds to ionic solids with decreased density, that is (b)-(iii).
Vacancy defect occurs mainly in non-ionic solids when atoms are missing from their lattice points.
The absence of atoms reduces the mass without significantly changing the volume,
so the density of the solid decreases.
Hence, vacancy defect matches with non-ionic solids and decreased density, that is (c)-(i).
Interstitial defect occurs in non-ionic solids when extra atoms occupy interstitial positions in the lattice.
This increases the mass of the solid while the volume remains almost constant, leading to an increase in density.
Thus, interstitial defect corresponds to non-ionic solids with increased density, that is (d)-(ii).