Multiple choice

Air is a________.

  1. gas

  2. atmosphere

  3. mixture of gas

  4. none of the above

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

Air is a homogeneous mixture of several gases, primarily nitrogen (about 78%), oxygen (about 21%), and small amounts of argon, carbon dioxide, and other gases. It is not a pure substance or just 'gas'.