Coal Mine Rescue Field Test 3 Taken from the 2018 NMRA Post 6 Mine Rescue Contest (Day 1) held in Cadiz, OH Progress Indicator: Question 4 of 10 4.  ____________ determines where a gas will stratify in still air in the mine (whether it will rise or fall). Choices: The atomic number The chemical index Poisson’s Ratio Specific gravity None of the above