Question

The one P-T-V combination at which solid, liquid and vapour are in equilibrium, is called

(a) Critical point

(b) Triple point

(c) Saturation point

(d) None of the mentioned

I have been asked this question at a job interview.

This interesting question is from Phase diagrams and Phase Rule-I topic in section Multiphase Equilibrium of Chemical Process Calculation

Answer 1

The correct answer is:

(b) Triple point

The triple point is the unique combination of temperature and pressure at which all three phases (solid, liquid, and vapor) of a substance coexist in equilibrium.