Solid State - Result Question 27
####27. The correct statement(s) regarding defects in solids is/are
(a) Frenkel defect is usually favoured by a very small difference in the sizes of cation and anion
(1999)
(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.
