What would happen if there is no oxygen in atmosphere?

Answer 1

plenty would happen!

our lungs would either completely fail and we would have been extinct a long time ago, or we would have evolved with lungs that could use another gas. also, there would be no such thing as fire, as fire needs oxygen to burn, and there is no substitute for it. also, and I could be very wrong about this as this is merely what I think, but water could become much more scarce than it is as there would be no oxygen in the atomosphere to react with the hydrogen to create water, so there would be little, if any water in the world. Trees would either not exist, or, like us, would have learned to survive on something like nitrogen because you can't have carbondioxide without the dioxide. you just have carbon, which isn't a gas. to sum it up, the world would be unfathomably different, if it even existed at all. or perhaps it would have ended up more like Venus or Mars? So yes, oxygen is VERY important. undoubtably the most valuable substance in the world, and thank God it's one of the most common!

Answer 2

Without oxygen in the atmosphere, most living organisms, including humans, would be unable to survive as we require oxygen for respiration. Many combustion processes would not occur, leading to the inability to create fire, and materials such as wood, coal, and gas would not burn. The lack of oxygen would also disrupt the Earth's ecosystem and lead to widespread extinction of aerobic organisms.