Read the Assertion and Reason below and choose the correct option. — Solid State Chemistry Question

💡 Solution & Explanation

Heating alkali halides in alkali metal vapour causes metal atoms to deposit on the surface. Halide ions diffuse to the surface to combine with them, leaving behind anion vacancies. Electrons from the ionized metal atoms diffuse into the crystal and occupy these vacancies. Both statements are true. However, the definition of an F-centre (Reason) does not explain *why* or *how* the vacancies are formed (Assertion). Therefore, correct answer is B.