First Aid Exam Taken from the 2014 Southwest Regional Mine Rescue Contest held in Carlsbad, New Mexico Progress Indicator: Question 5 of 25 5.  Carbon Monoxide is explosive and flammable.  It’s explosive range in normal air is _________ percent. Choices: 12.0 to 75.0 13.0 to 76.2 12.5 to 74.2 12.5 to 72.4