The mass number of an atom is equal to the sum of protons and neutrons in the nucleus. A helium atom has 2 protons and 2 Neutrons. What js the mass number of this atom

Answer 1

The mass number of an atom is calculated by adding the number of protons and neutrons together.

For a helium atom, which has 2 protons and 2 neutrons:

\[ \text{Mass number} = \text{Number of protons} + \text{Number of neutrons} = 2 + 2 = 4 \]

Therefore, the mass number of a helium atom is 4.