Chemistry - Solid State Question with Solution | TestHub

Option A is incorrect. Schottky defects are point defects (vacancies), not dislocation defects. Dislocation defects are line defects.

Option B is incorrect. Doping NaCl with Al³⁺ creates two cationic vacancies per Al³⁺ ion to maintain charge neutrality, as Al³⁺ replaces three Na⁺ ions.

Option C is correct. Arsenic (As) is a Group 15 element, and when added to silicon (Si), a Group 14 element, it acts as a donor impurity, providing extra electrons and forming an n-type semiconductor.

Option D is incorrect. Vacancy defects reduce the number of atoms in the crystal lattice, thereby decreasing the overall packing fraction.