question_answer 8)

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

Answer:

Mass number of Helium = 4 Number of protons = 2 Number of neutrons(n) = Number of Mass(A) — Number of proton (P)                                                                 = 4 – 2 = 2 Thus, No. of neutrons = 2