Which human activity will decrease air pollution? a. burning crops b. burning household garbage c. driving a hybrid car d. using coal to produce energy

D. using coal to produce energy

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.