What is the total pressure of contained if it contains 0.5 fraction of O2 with partial pressure 3 Pa, 0.3 fraction of H2 with partial pressure 5 Pa, 0.2 fraction of CO2 with partial pressure 15 Pa?

Correct Answer: 6 Pa
Total pressure = 0.5*3 + 0.3*5 + 0.2*15 = 6 Pa.