Question

A compound is formed by cation C and
anion A. The anions form hexagonal close packed
(hcp) lattice and the cations occupy 75% of
octahedral voids. The formula of the compound is:
[NEET-2019​

Answer 1

Answer: C3A4 is the formula of the solid.

Explanation:

Refer attachment for explanation!!!

Answer 2

Question: A compound is formed by cation C and  anion A. The anions form hexagonal close packed  (hcp) lattice and the cations occupy 75% of  octahedral voids. The formula of the compound is:

Solution: Anions (A) are in hcp, so number of anions (A) = 6

Cations (C) are in 75% O.V., so number of cations (C)

$=6 \times \frac{3}{4}\\=\frac{8}{4} \\=\frac{9}{2}$

So formula of compound will be:

$\boxed{C_\frac{9}{2}A_6 \implies C_9A_1_2 }$

$:\implies \boxed{C_9A_1_2 \implies C_3A_4}$