I haven't done Scientific Saturday in a long time! Partly because I didn't know what to do it on, and partly because I had forgotten about it. But I'm going to start back into it, if you will allow me. Especially now that we have been back in school for over two months now!  

Oxygen is a gas that is essential to life here on earth. You could only exist for about three minutes without oxygen. People and animals use oxygen and give off carbon dioxide, while plants use carbon dioxide and give off oxygen. God has designed the system perfectly! Since oxygen is so important, you may wonder "Why?" when I tell you that only about 21% of the atmosphere is composed of oxygen! God makes no mistakes, remember? God sure knew what he was doing not to make 100% of the atmosphere oxygen.

Besides the fact that plants could not survive, we would also have a huge problem with fires if there was that much oxygen in the air. We would not be able to control fire. In some ways, fire is a good thing. You use fire everyday! We take it for granted, but we use it! But fire is also very dangerous. Fire can seriously injure and/or kill. If the atmosphere was 100% oxygen, heated iron would burn strongly, as well! I have a feeling that we would not live very long if there was that much oxygen in the air!

God also knew what he was doing when he made almost 80% of the atmosphere nitrogen. Nitrogen is inert, which means that it will not quickly combine with other gases. Having so much nitrogen in the air "waters down" the oxygen in the air. As I mentioned before, if we had pure oxygen, the earth would burst into flames! The nitrogen keeps that from happening.