How is acid rain produced? CO 2 molecules react with H 2 O molecules in the cloud to form a solution that has a pH much lower than 7.0. None of these is the correct answer. Acid rain is made up of a combination of sulfur dioxide and nitrogene oxide, not water. CO 2 molecules react with H 2 O molecules in the cloud to form a solution that has a pH much higher than 7.0. Carbonic acid is produced when oxygen molecules are depleted from the clouds. .