Question

Which of the following is NOT a characteristic of Schottky defect?

• A. After defect stoichiometry, the crystal remains unchanged.
• B. After defect neutrality, the crystal's structure remains unchanged.
• C. After defect density of crystal remains unchanged
• D. It is a vacancy defect.

Hint:

Missing ions mean the crystal gets less dense.

Answer 1

The Correct Option is C

Step 1: Picture:
Remove one Na+ and one Cl- from NaCl. The formula ratio stays 1:1 and the charge stays balanced.

Step 2: Density:
The same unit-cell volume now holds fewer ions, so the mass per unit volume drops.

Step 3: Verdict:
A, B and D describe true features. C claims density is unchanged, which is false.

Final Answer:
The claim of unchanged density is wrong. \[ \boxed{C} \]