Question 14
How much of air is nitrogen by volume, and how reactive is it?
The right answer is the one marked above.
About 78.1% of air by volume, and it is a gas of very low reactivity.
21% is oxygen's share; 0.03% is carbon dioxide's. Nitrogen does react at very high temperatures — with oxygen, hydrogen, carbon and silicon, and with metals such as magnesium — and in a strong electric arc it combines with oxygen to form nitric oxide, which is what happens naturally during lightning.