Final answer:
About 78% of the Earth's atmosphere is nitrogen, which translates to over 20 million tons over every square mile. It is essential for life, forming part of proteins and genetic materials in organisms.
Step-by-step explanation:
The atmosphere of Earth is composed largely of nitrogen. By volume, 78% of our air is nitrogen, making it the most abundant gas in our atmosphere. This percentage translates to a staggering amount, with more than 20 million tons of nitrogen present over every square mile of Earth's surface. Nitrogen is not only pervasive in the atmosphere; it is also a crucial element for life, being a key component of proteins and genetic material, DNA and RNA, for all plants and animals. In industrial applications, pure nitrogen is often obtained through the process of fractional distillation of liquid air.