Question

what is atom I no. and atomic mass no?

Answer 1

Atomic number is the number of protons or electrons present in an element . Atomic mass is the sum of the number of protons and neutrons.

Answer 2

The mass no (symbol A, from the German word Atomgewicht (atomic weight) also called atomic mass number or nucleon number, is and the total number of proton and neutrons, (together known as nucleons) in an atomic nucleus.