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

Sum

Atomic mass = 4u

Atomic mass = Number of neutrons + Number of protons

4 = Number of neutrons + 2

Number of neutrons = 4 − 2

Number of neutrons = 2

∴ The number of neutrons in a helium atom = 2.

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Chapter 4 Structure of the Atom
Intext question | Q 8. | Page 41

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