Check sibling questions

Helium atoms have an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have?



We know that nearly all the mass of an atom is because of the nucleus.

The mass of the nucleus is due to the presence of protons and neutrons .


Mass of a proton = Mass of a neutron = 1u



Atomic mass = 4u

Number of protons = 2 → Mass = 2u


Mass of neutrons = atomic mass - mass of protons

              = 4u - 2u

                             = 2u


2 u →  2 neutrons

Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class

Ask a doubt
Maninder Singh's photo - Co-founder, Teachoo

Made by

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo