Question

What is the vapor pressure of 40% gas in a system with partial pressure 20 mm Hg?

(a) 5 mm Hg

(b) 10 mm Hg

(c) 20 mm Hg

(d) 50 mm Hg

This question was addressed to me during a job interview.

Question is from Vapor-Liquid Equilibria in Binary Systems topic in section Two Phase Gas – Liquid Systems, Phase Rule and Vapor-Liquid Equilibria of Basic Chemical Engineering

Answer 1

Correct choice is (d) 50 mm Hg

For explanation I would say: Vapor pressure = 20/0.4 = 50 mm Hg.