Question

The main substances in air are N 2 (nitrogen), O 2 (oxygen), CO 2 (carbon dioxide), H 2 O (water), and Ar (argon). Which of these substances are elements? Which are compounds? Which are molecules?

Answer 1

N (Nitrogen), O (oxygen) and Ar (argon) are elements found on the periodic table, H20 ( water) is a molecule and CO2 ( carbon dioxide ) is a compound.