Help me get this answer right!!

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.

the question isn't complete here so i can't right an answer '_'

not always but somethings can be reproduced in a laboratory.