MolSynapsequestion bank

MolSynapse / Question bank / Solid State / Close packing, voids and radius ratio

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ss090

In one unit cell of an fcc (ccp) lattice, which statements are correct?

AThe 12 edge-centre octahedral voids each contribute $\frac{1}{4}$ of a void to the cell.
BThe tetrahedral voids lie at the centres of the 12 edges.
CThere are 4 octahedral voids in total.
DThere are 8 tetrahedral voids in total.

Answer: A, C, D

The body-centre void counts 1 and the 12 edge centres count

12 \times \frac{1}{4} = 3

, giving 4 octahedral voids. The 8 tetrahedral voids lie inside the cell on the body diagonals, at

\frac{1}{4}

the diagonal from each corner, not on the edges.

Practice Solid State More on Close packing, voids and radius ratio

Previous questionNext question

More questions on Close packing, voids and radius ratio