IIT-JEE 2009 · Paper 1 · Chemistry Q9

ChemistryMultiple correct+4 / -1Question 9 of 60

The correct statement(s) regarding defects in solids is(are)

Frenkel defect is usually favoured by a very small difference in the sizes of cation and anion

Frenkel defect is a dislocation defect

Trapping of an electron in the lattice leads to the formation of F-center

Schottky defects have no effect on the physical properties of solids

Answer and worked solution

Official answer: B, C

(A) Frenkel defects are favoured by a large difference in size (the small cation fits into interstitial sites, e.g. AgCl, ZnS). False.
(B) In a Frenkel defect an ion is displaced (dislocated) from its lattice site to an interstitial site, so it is called a dislocation defect. True.
(C) An electron trapped in an anion vacancy is an F-centre. True.
(D) Schottky defects lower the density, so they do affect physical properties. False.

The official key accepts (B, C) or (C) alone.

(B), (C)

Topics:Point defects

IIT-JEE 2009 · Paper 1, Chemistry question 9