Question

What is the most common crystal structure?

(a) Face-centered cubic and square packed structures

(b) Face-centered cubic and hexagonal close-packed structures

(c) Square packed structures and hexagonal close-packed structures

(d) Square packed structures and parallelogram packed structure

The question was asked in an online quiz.

Question is from Crystal Geometry topic in chapter Crystallization of Food Processing Unit Operations

Answer 1

Correct answer is (a) Face-centered cubic and square packed structures

To elaborate: A Face-centered cubic (FCC) unit cell contains atoms at all the corners of the crystal lattice and also at the center of all the faces of the cube whereas hexagonal close-packed (hcp) arrangement has a unit cell which consists of three layers of atoms. The top and bottom layers contain six atoms at the corners of a hexagon and one atom at the center of each hexagon.