Question

Correct statement(s) with respect to defects in solids is(are)

• A. In Schottky defect, atoms move from interior lattice sites to surface lattice sites
• B. Equilibrium concentration of defects remain unchanged with change in temperature
• C. A perfect solid is thermodynamically less stable than the solid with defects
• D. Common point defects in pure alkali halides are Frenkel-type

Hint:

Defects in solids play a crucial role in determining the properties and stability of materials. Schottky and Frenkel defects are common types, but they occur in different conditions.

Answer 1

The Correct Option is C

Step 1: Analyze each statement.
- Option (A): This is incorrect. In a Schottky defect, atoms are missing from the lattice, not moving from interior sites to surface sites. It involves the creation of vacancies in both the cation and anion sublattices.
- Option (B): This is incorrect. The equilibrium concentration of defects generally increases with temperature, as the thermal energy allows more atoms or ions to leave their lattice sites.
- Option (C): This is correct. A perfect solid is thermodynamically less stable than a solid with defects because defects lower the energy of the solid, making it more stable.
- Option (D): This is incorrect. Common point defects in pure alkali halides are typically Schottky-type defects, not Frenkel-type. A Frenkel defect involves the displacement of an ion to an interstitial position, while Schottky defects involve missing ions.
Final Answer: \[ \boxed{\text{The correct answer is (C).}} \]