Chemistry - Solid State Question with Solution | TestHub

Fluorite $({\mathrm{CaF}}_2)$: cations form ccp, anions fill all 8 tetrahedral voids.

(A) Cation has 8 anion neighbours, anion has 4 cation neighbours: 8 : 4, true.

(B) A tetrahedral void sits a/4 along each axis from the nearest cation: distance = √3a/4, true.

(C) The anions form a simple cubic lattice of edge a/2: shortest anion-anion distance a/2, true.

(D) Cations form a ccp lattice; nearest cation-cation distance is a/√2, not a/2: false.

Answer: (A), (B), (C).