Q. Which of the following is the third most abundant gas in atmosphere? Answer:
Argon
Notes: The most abundant naturally occurring gas is nitrogen (N2), which makes up about 78% of air. Oxygen (O2) is the second most abundant gas at about 21%. The inert gas argon (Ar) is the third most abundant gas at 0.93%. Carbon dioxide, helium, ozone, and hydrogen are found in lesser quantities. Apart from these gases, tiny dust particles are also present in the air.