Answer the following question given this paragraph: 

Rutherford’s experiment showed that the vast majority of the mass of an atom is concentrated in its nucleus, which is composed of protons and neutrons. The mass of an electron is very small compared to the mass of a neutron or proton, so the electrons in an element do not contribute much to the total mass. The mass number is defined as the total number of protons and neutrons in an atom. Remember that both protons and neutrons have a mass of approximately 1 amu. Knowing the mass number and the atomic number of an atom therefore allows you to determine the number of neutrons present in that atom by subtraction:.


Q: According to rutherford, where is the vast majority of the mass of an atom located?

 Choices:

- the cytoplasm

- the shell

- the electrons

- the nucleus

A:
the nucleus
