Does anybody know what is exactly inside...?

Question

divers "air bottles" or astronauts backpack.i mean what is exact mixture inside?
sorry for my bad english :)))))

Answer 1

Spacesuits use pure oxygen to minimize the pressure required. Shallow divers use plain old compressed air (regular air is used in the ship/station, though, because pure oxygen creates a fire hazard). Professional deep divers use a mixuture of helium and oxygen to avoid nitrogen narcosis (nitrogen is deadly at high pressures).

Answer 2

compressed air...mostly Nitrogen.