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

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

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

What is the total number of naturally occurring elements?

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

What is the maximum number of electrons that can occupy the first shell of an atom ?