Question

The particle not present in an ordinary hydrogen atom is:
A) Proton
B) Neutron
C) Nucleus
D) electron

Answer 1

The periodic table consists of different chemical elements. Hydrogen is the first element with atomic number $1$. The atomic number of hydrogen is $1$ there will be one proton and the mass number is also $1$. Thus, an ordinary hydrogen atom has one proton and one neutron.

Complete answer:
Atoms are tiny particles consisting of sub-atomic particles called protons, neutrons and electrons. Electrons are negatively charged subatomic molecules and protons are positively charged subatomic particles, neutrons are neutral charged subatomic particles.
Hydrogen has three isotopes namely proton, deuterium and tritium. The isotopes are the chemical elements with the same atomic number but different mass number. Proton is the isotope of hydrogen with mass number $1$ . Deuterium is the isotope with mass number $2$and tritium consists of mass number $3$.
Hydrogen atoms have proton, electrons. Inside the nucleus every atom consists of protons and neutrons. Here in the hydrogen atom the nucleus will be present without neutrons.
An ordinary hydrogen atom is a proton, thus it consists of only protons and electrons. The mass number is $1$. Thus, an ordinary hydrogen atom does not have neutron subatomic particles.
The correct answer is Option B: Neutron.

Note:
Though generally hydrogen has atomic number $1$, the isotopes were different from normal atoms. This isotopic labelling or substitution is useful in determining the reactivity of compounds. The general or ordinary isotope of hydrogen is proton with $99.9\%$ .