Nitrogen, $\mathrm{N}_{2}(g),$ oxygen, $\mathrm{O}_{2}(g),$ carbon dioxide, $\mathrm{CO}_{2}(g),$ and water vapor, $\mathrm{H}_{2} \mathrm{O}(g),$ are all gases found in the atmosphere.
a. Draw the structural formula for each and include lone pair electrons.
b. Draw the Lewis dot structure for water.
c. Which molecules are polar and which molecules are nonpolar?
d. Which one of the four substances is naturally found as a liquid, a solid, and a gas on Earth?