Atomic mass of an element is equal to the sum of number of

Regarding the atom of a chemical element, the magnetic quantum number refers to –

The mass number of a nucleus is

What is the mass number of an element, the atom of which contains two protons, two neutrons and two electrons?

The number of electrons and neutrons in an element is 18 and 20 respectively. Its mass number is

The number of maximum electrons in N shell is