Question

The _________ contains the majority of the mass of the atom but is much ________ than the atom.

Answer 1

A. 
nucleus hold protons and neutrons that contain the mass. but is smaller due to the electron cloud making the atom bigger.

Answer 2

The nucleus has almost all the mass of the atom, but only a tiny tiny tiny tiny tiny portion of the atom's volume. The rest of the atom is the electron cloud and mostly empty space. I read that the nucleus in the middle of one atom is like a bunch of grapes in the middle of Texas !