Question

Which of the following is not a sub- atomic particle of an atom?
A.Electrons
B.Protons
C.Nucleus
D.Neutrons

Answer 1

Hint: To answer this question, you must recall the various sub- atomic particles and their properties. They are also known as elementary particles as they are self- contained units of energy and matter that are the fundamental constituents of all matter.

Complete answer:
Sub- atomic particles are the fundamental particles of matter that together compose an atom. There are three sub- atomic particles that are, electrons, protons and neutrons. Electrons are negatively charged, protons are positively charged while neutrons are neutral particles and carry no charge. The sub- atomic particles are present in such a way that the electrical neutrality of an atom is maintained.
The protons and neutrons together constitute the nucleus of an atom around which the electrons revolve in fixed orbits. Thus, we can say that there are three sub- atomic particles namely electrons, protons and neutrons. Nucleus is not a sub- atomic particle.

Thus, the correct answer is C.

Note:
Although electrons, protons and neutrons are sub- atomic particles, they have different sizes and masses. Protons and neutrons have a very large size as compared to electrons. A neutron and a proton have almost similar masses and their mass is given by one atomic mass unit. The mass of electrons is negligible as compared to that of protons and neutrons and thus the atomic mass is denoted solely as the sum of the mass of protons and neutrons. Or in other words, the mass of the atom is the same as the mass of the nucleus.