Question

How are atomic number and mass number related to the number of protons and neutrons inside the nucleus of an atom?

Answer 1

Atomic number is equal to the number of protons.
Atomic mass is equal to the sum of number proton and number neutron .

Answer 2

Atomic no. means the no. of proton or neutron situated in a nucleus. i.e. p+ or e- = atomic no.

atomic mass no. means protons + neutrons in the nucleus. Electron does not have a mass hence all the mass of atom depends upon proton and neutrons. i.e. atomic mass no. = p+ and n.