Which of the following subatomic particles contributes toward the atomic mass of hydrogen?
a. element
b. proton
c. electron
d. neutron

The correct option is: b. proton

Explanation:

Hydrogen is the first and the lightest chemical element of the periodic table, having mass number 1.008 and atomic number 1. It is an s-block element that belongs to the group 1 of the periodic table.

The most abundant isotope of hydrogen is protium (). In the elemental state, it has one electron, one proton and zero neutrons.

Since, the mass number of a chemical element = the number of (protons + neutrons) present in the nucleus

⇒ atomic mass of hydrogen = 1 + 0 = 1

Therefore, only the proton contribute to the atomic mass of the hydrogen.