Is there oxygen on Mars?
There is a small amount of gaseous oxygen in the atmosphere of Mars, about 0.13%. Most of the oxygen in the atmosphere is there as carbon dioxide, CO2. This gas makes up 95% of the very, very thin atmosphere.
However, there is still quite a lot more oxygen on Mars - as iron oxides. These are mostly what give Mars its red color. It would be theoretically possible to extract both pure oxygen and pure iron from these rocks, which is probably where the oxygen for any Mars colonists would need to come from.
Nobody knows whether or not there is enough oxygen on Mars. NASA are looking into it to see if there is any water on Mars or any living creatures with a robot. If they eventually find something, then this gives us more evidence that there is oxygen on Mars. Until that day then no one will know but a small robot connected to NASA called the Mars rover.
There is oxygen on Mars. It's just not in the form of oxygen gas in the atmosphere, and there isn't enough atmosphere of any kind to keep your lungs from rupturing anyway. That said, if you could collect the oxygen on Mars and compress it to a reasonable density, sure, you could breathe it. It's just oxygen, it doesn't matter what planet it came from.
The oxygen in Earth's atmosphere exists as a result of the living things on it (such as plants and bacteria) absorbing carbon dioxide and replacing it with oxygen. Before life on earth, there was very little oxygen in the atmosphere. Given that there is no life on Mars (or at least, none that we know of), the biological processes that created oxygen in Earth's atmosphere do not take place on Mars.
Mars has too LITTLE OXYGEN for humans to live on. Earth's atmosphere has about 21% Oxygen at 1 atmosphere of pressure, but you can live on higher percentages of oxygen at lower pressures such as in NASA spacesuits. While Carbon Dioxide is toxic to humans at high concentrations, you would likely suffocate to death from lack of oxygen first on Mars. Search Wiki: Atmosphere of Mars "The atmosphere on Mars consists of 95% carbon dioxide…