——— ———— used squares to make Mendelś ———- easier to understand.

the punnet used to make genetics of the pea plant easier to understand

d.

hope to be marked brainliest

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.