Question

The sum of the number of protons and neutrons in an atom is known as it

Answer 1

mass number

A=Z+N

where a =mass number

Answer 2

$\huge\bold{Answer}$

___________________________________

The sum of the number of protons and neutrons in an atom is known as its $\bold{mass\: number}$.

Eg:-

Hydrogen has a mass no. 1

it has 1 proton but no neutron in its nucleus.

___________________________________

Hope it helps you♐