Question

Protons and neutrons are also called _______________.
(A) nucleons
(B) isotope
(C) isobars
(D) elements

Answer 1

Hint: Matter is anything that occupies space and has some mass. An atom is the basic structural unit of matter. It constitutes the smallest part of the Elements and Compounds. Initially when Atom was first discovered by John Dalton it was considered to be indivisible however later the subatomic particles were discovered resulting in the atomic structure we know today.

Complete answer:
It was J.J Thomson who gave the plum pudding model or raisin pudding or watermelon model and first discovered the electrons. Electrons are the negatively charged particles moving around a small nucleus of the atom. The nucleus consists of a very small mass of the atom and was first discovered by Rutherford using the Alpha particle scattering experiment. Nucleus is the place where most of the mass and positive charge is present or concentrated.
Nucleus consists of 2 subatomic particles- Neutrons (Neutral particles) and Protons (Positively charged particles). Neutrons were first discovered by Chadwick in 1932. The charge of the protons and electrons is the same in magnitude but opposite in nature of a gaseous neutral atom.
Atomic number (Z) is the number of protons or the number of electrons in a neutral gaseous atom. Atomic mass (A) is the total number of protons and neutrons in an atom.
These protons and neutrons are collectively called “Nucleons”.
So option (A) is correct.

Note:
The Nucleons are made up of quark. There is a strong force between the protons and neutrons that holds them inside the nucleus. The electrons are not considered to be nucleons. Thus we can say that the Mass number or Atomic mass is actually the number of nucleons present inside the atom.