At 20°c, a sample of h2o liquid and a sample of co2 gas each have the same average kinetic energy. why is one a liquid and the other a gas at this temperature?

Water has a strong hydrogen bond which is absent in carbon (IV) oxide.

The net forces of attraction between water molecules is greater than the kinetic energy thus water molecules cannot move far away from each other but slide over each other.

Carbon (IV) oxide molecules are held together by weak Van der waals forces which are overcome by the kinetic energy of the molecules. This makes the molecules move easily in random directions.

that's what i got you can count the number of atoms