Multiple choice

Which of the following is a greenhouse gas?

  1. O2

  2. N2

  3. CO2

  4. CO

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

CO2 is a primary greenhouse gas that absorbs and re-emits infrared radiation. Unlike O2 and N2 which are transparent to infrared, CO2's molecular structure allows it to trap heat.