a. Contains very little of the mass of an atom - The nucleus contains almost all of the mass of an atom. Very little mass is found outside the nucleus.

b. Occupies a large part of the volume of an atom - The nucleus occupies a very small volume. Think of the golf ball analogy - If you think of a golf ball on the 50 yard line of a football field as the nucleus the electrons surrounding the electron would be about at the seat farthest away from the golf ball.

c. Contains protons, neutrons, and electrons - The nucleus contains only protons and neutrons. All electrons are found outside the nucleus.