Question

What is the partial pressure of 20% gas in a system with vapor pressure 10 mm Hg?

(a) 2 mm Hg

(b) 10 mm Hg

(c) 50 mm Hg

(d) 100 mm Hg

This question was posed to me in an international level competition.

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

Answer 1

Right answer is (a) 2 mm Hg

Easiest explanation: Partial pressure = 0.2*10 = 2 mm Hg.