Trivia: What gas makes up 95% of Mars’ atmosphere?
Ozone
Oxygen
Carbon dioxide
Water vapor
Correct Answer: Carbon dioxide
So why is this answer correct? : Like Earth, Mars has a unique atmosphere, which is 95% carbon dioxide, 3% nitrogen, 1.6% argon, and trace amounts of water, carbon monoxide, and methane. Earth’s most plentiful atmospheric gasses, by contrast, are nitrogen (78%) and oxygen (21%), creating a habitat that supports organic life.