Question

Pure iron exists in ________ allotropic forms.

(a) One

(b) Two

(c) Three

(d) Four

I have been asked this question in an internship interview.

This intriguing question comes from Iron-Carbon System and their Alloys in section Constitution of Alloys and Phase Diagrams of Engineering Material & Metallurgy

Answer 1

Right choice is (c) Three

To elaborate: Allotropy is defined as the possibility of the existence of two or more different crystal structures for a substance depending on temperature. Pure iron is an allotropic metal that exists in three forms. These allotropic forms are α iron, ϒ iron, and δ iron.