A compound is formed by cation C and anion A. The anions form hexagonal close packed (hcp) lattice and the…

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:
A $C_2A_3$
B $C_3A_2$
C $C_3A_4$
D $C_4A_3$

Detailed Solution

Anions (A) form hcp, so number of anions per unit cell $=6$, and number of octahedral voids $=6$. Cations (C) occupy 75% of octahedral voids: number of cations $=6\times\frac{3}{4}=\frac{18}{4}=\frac{9}{2}$ Formula: $C_{9/2}A_6\Rightarrow C_9A_{12}\Rightarrow C_3A_4$

Close Packed Structures – Voids in past papers

2 questions from this chapter have appeared across 2 exam years.

Keep going

Practise Close Packed Structures – Voids All 2 questions This chapter in 2019