Answer:
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 (
). <u>In the elemental state, it has one electron, one proton and zero neutrons.</u>
Since, <u>the mass number of a chemical element = the number of (protons + neutrons) present in the nucleus</u>
⇒ atomic mass of hydrogen = 1 + 0 = 1
<u>Therefore, only the proton contribute to the atomic mass of the hydrogen.</u>