Question

Proton is:
A. An ionized hydrogen atom
B. An $\alpha$ particle
C. A fundamental particle
D. nucleus of heavy hydrogen

Answer 1

Hint: We should know what a proton is and what it represents. By losing one electron, the hydrogen atom becomes ionized. Helium is an alpha particle. Deuterium is known as heavy hydrogen.

Complete Solution :
Proton is a subatomic particle. It is found in the nucleus of the atom. The proton carries one positive charge and one mass number.
The proton is represented as follow:
$\text{p}$ , ${\text{p}}^{\text{ + }}$

An atom is represented as follows:
${}_{\text{Z}}^{\text{m}}\text{X}$
Here, X is the atomic symbol.
Z is the atomic number.
M is the mass number.

The proton number represents the atomic number and the sum of proton and neutron numbers represents the mass number. For a neutral atom, the electron number is equal to the proton number.
 The atomic symbol of hydrogen is as follows:
${}_{\text{1}}^1\text{H}$

The hydrogen atom has one proton, zero neutron and one electron.
An ionized hydrogen atom means hydrogen lost one electron so, the atomic symbol of an ionized hydrogen atom is:
${}_{\text{1}}^1{\text{H}}^{+}$

an ionized hydrogen atom has only one proton so the proton can be represented as an ionized hydrogen atom.
The atomic symbol of alpha-particle is as follows:
${}_2^4\text{He}$

The alpha particle has two protons, two neutrons, and two electrons. Alpha particle contains two protons but it does not represent a single proton.

Proton is a subatomic particle that constitutes the nucleus of an atom so it is a fundamental particle.
Deuterium is the isotope of hydrogen. It has one neutron with one proton. So, its mass is more than hydrogen, so it is known as heavy hydrogen.
The atomic representation of heavy hydrogen is as follows:
${}_{\text{1}}^2\text{H}$

Heavy hydrogen has one electron and two neutrons whereas a proton has no electron and neutron so a proton cannot be represented as heavy hydrogen.
So, a proton is ionized hydrogen and a fundamental particle.

Therefore, option (A) ionized hydrogen and (C) a fundamental particle are correct.

Note: The species having the same number of protons but a different number of neutrons hence different mass numbers are known as isotopes. The electron, proton, and neutron are known as fundamental particles. During ionization of an atom, only electron numbers change on the proton and neutron number. Proton is discovered by Rutherford.