A Frenkel defect involves
Amissing pairs of ions (typical)
Bextra electrons trapped in vacancies
Ca cation moving from its lattice site to an interstitial position
Dsubstitution by a foreign ion
Answer & Solution
Correct answer: C. a cation moving from its lattice site to an interstitial position
1. Frenkel defect is a type of point defect in ionic solids where a smaller ion (usually cation) leaves its lattice site for an interstitial site.
2. Stoichiometry is preserved; density is unchanged.
3. It is common in AgCl, AgBr, ZnS — substances with large size disparity between cation and anion.
_Source: Maharashtra Balbharati Std XII Chemistry, Ch 1 "Solid State" §1.10_
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