Solid State - Result Question 27
27. The correct statement(s) regarding defects in solids is/are
(1999)
(a) Frenkel defect is usually favoured by a very small difference in the sizes of cation and anion
(b) Frenkel defect is a dislocation defect
(c) Trapping of an electron in the lattice leads to the formation of F-centre
(d) Schottky defects have no effect on the physical properties of solids
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Answer:
Correct Answer: 27. (b, c)
Solution:
- (a) Wrong statement : A small difference in sizes of cation and anion favour Schottky defect while Frenkel defect is favoured by large difference in sizes of cation and anion.
(b) Correct statement : In Frenkel defect the smaller atom or ion gets dislocated from its normal lattice positions and occupies the interstitial space.
(c) Correct Statement : In F-centre defect, some anions leave the lattice and the vacant sites hold the electrons trapped in it maintaining the overall electroneutrality of solid.
(d) Wrong statement : In Schottky defect, some of the atoms or ions remaining absent from their normal lattice points without distorting the original unit cell dimension. This lowers the density of solid.
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