2001 AIPMT The Solid StateClose Packing: Coordination Number Easy Question 44 of 45 in The Solid State

Zn converts from its melted state to its solid state; it has HCP structure, then find out number of nearest atoms : -

A 6
B 8
C 12
D 4

The answer is C.

Solution

In hexagonal close packing (hcp), each atom touches 6 atoms in its own layer, 3 atoms in the layer above and 3 atoms in the layer below.
Coordination number $= 6 + 3 + 3 = 12$
(Cubic close packing, ccp/fcc, also has coordination number 12.)
So each Zn atom has 12 nearest neighbours.

Concept Coordination number in hcp

The Solid State in past papers

45 questions from this chapter have appeared across 23 exam years.