Question

Define the mass number of an element.

Answer 1

Mass number of an element:

The sum of number of protons and number of neutrons in an atom is known as the mass number of that element.

Example:

1. In a Nitrogen $\mathbf{\left(}\mathbf{N}\mathbf{\right)}$ atom, there are $7$ protons and $7$ neutrons.
2. Thus, the mass number of Nitrogen is$=7+7=14$