Q11 / 60 · JEE Advanced 2009 (Paper 1) · Chemistry

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
  • Correct answer
    B
    Frenkel defect is a dislocation defect
  • Correct answer
    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

Solution

(a) Wrong Frenkel defect is favoured when the difference in ionic radii is very large. In the given case Schottky defect is favoured. (b) Correct Frenkel defect arises due to dislocation of smaller ion from its normal lattice point to the interstitial space. (c) Correct When alkali metal in the gaseous state is passed over salts like $\mathrm{NaCl}$, electrons from metal are trapped in the interstitial space giving rise to F-centre defect which is a type of Frenkel defect. (d) Wrong Schottky defect affects physical properties of solids.

Hence, the correct answer is options: 'B', 'C'.

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