Why are hydrogen and helium liquid on the outer planets?

What provides structure to the human body?

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

Achange in the number of neutrons in an atom will change an blank . when the number of protons changes in an atom, a new element will form.