Question

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

Answer 1

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Given: Atomic mass of helium atom = 4u, 2 protons in helium nucleus

Atomic mass = number of protons + number of neutrons

4 = 2 + number of neutrons

Number of neutrons = 4 – 2 = 2

Hence, Helium has 2 neutrons.