Concept:The nucleus is the dense, positively charged core of an atom that contains the heavy sub-atomic particles.
Explanation:The nucleus contains protons and neutrons.
Protons carry a positive charge of
+1.
Neutrons carry no charge, so they are electrically neutral.
These two particles are jointly called nucleons.
The number of protons is the atomic number (
Z), while the sum of protons and neutrons gives the mass number (
A).
Electrons carry a negative charge of
−1 and are not found in the nucleus.
Electrons move around the nucleus in energy levels or shells.
Answer:A. neutron and proton