Question

Which from following ionic crystals exhibits Frenkel defect?

• A. \(\text{ZnS}\)
• B. \(\text{NaCl}\)
• C. \(\text{KCl}\)
• D. \(\text{KBr}\)

Hint:

Frenkel defect needs a small cation and a large size difference between ions, as in ZnS.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In a Frenkel defect, a small cation leaves its lattice site and sits in an interstitial position. It needs a large difference in size between cation and anion, and low coordination number.

Step 2: Apply:
\(\text{Zn}^{2+}\) is small and \(\text{S}^{2-}\) is large, so ZnS shows Frenkel defect (and AgCl, AgBr also do).
NaCl, KCl and KBr have cations and anions of similar size, so they show Schottky defect instead.

Final Answer:
ZnS shows Frenkel defect, option (A). \[ \boxed{\text{ZnS}} \]