Question

Helium atom has atomic mass of 4u and has 2 protons in its nucleus. How many nuetrons does it have

Answer 1

Helium has 2 neutron

Answer 2

Explanation:

Mass number of helium is equal to its atomic mass but has no units.

Mass number of helium = 4

No. of proton in nucleus = 2

Atomic number (z) of the element = 2

No. of neutrons (n) = A = -4 - 2 = 2