Question

The fundamental particle with least mass is
A.Proton
B.Alpha particle
C.Electron
D.Neutron

Answer 1

Hint:To answer this question, you must be familiar with various sub- atomic properties and their properties. We know that the mass of an atom is constricted in the nucleus of the atom. Using this, we can easily determine the particle with least mass.

Complete step by step answer:
Sub- atomic particles are tiny particles of matter that together constitute an atom. There are three subatomic particles, which are namely electrons, protons and neutrons. Electrons are negatively charged particles, protons are positively charged while neutrons are neutral and carry no charge. The protons and neutrons are present in the nucleus of the atom and the electrons revolve around it in fixed orbits.
Although electrons, protons and neutrons are all sub- atomic particles but are all of different sizes and masses. When we compare their masses, we find that the mass of electrons is extremely small as compared to neutrons and protons. This is because there is also a significant difference in the sizes of these particles. Protons and neutrons are very large in size as compared to electrons.
Alpha particle is a helium nucleus or helium cation carrying a charge of \[ + 2\] and thus has a mass of two protons and two neutrons combined.

Thus, the correct answer is C.

Note:
The mass of a proton and a neutron are approximately the same and is given by one atomic mass unit. However, neutrons are slightly heavier than protons but we generally assume them to be of the same mass. The mass of an electron is negligible as compared to that of neutrons and protons and thus the atomic mass is given as the sum of the mass of protons and neutrons.