5.9.1.1 the properties of different gases in the atmosphere

Question 1

For 200 million years, the proportions of different gases in the atmosphere have been much the same as they are today:
State what proportions

Answer 1

-about four-fifths (approximately 80%) nitrogen
-about one-fifth (approximately 20%) oxygen
-small proportions of various other gases, including carbon dioxide, water vapour and noble gases.

Question 2

What is a noble gas

Answer 2

any of a group of rare gases that include helium,

Question 3

Name examples of noble gases

Answer 3

neon, argon, krypton, xenon, and sometimes radon