What is the common name of ursa major?

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.

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.