Question

helium atom has an atomic mass of 4u and two protons in to nucleus . how many neutrons does it have

Answer 1

The mass of an atom is the sum of the masses of protons and neutrons present in its nucleus. Since helium atom has two protons, mass contributed by the two protons is (2 X 1) u = 2 u. Then, the remaining mass (4 — 2) u = 2 u is contributed by 2 neutrons.. Thus helium atom has two neutrons

Answer 2

The answer would be 2
Because it's atmoic mass 4 n protons r 2 so we subtract 4 and 2( A=no of protons + no of neutrons)
Hence answer is 2................!