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

CONCEPT:

• ATOMIC NUMBER: It is defined as the number of protons present in the nucleus. It is denoted by the letter Z.
• MASS NUMBER: The total number of protons and neutrons present in a nucleus is called the mass number of the element. It is denoted by letter A.

• For neutral atom,

1. Number of protons in an atom = Z
2. Number of electrons in an atom = Z
3. Number of nucleons in an atom = A
4. Number of neutrons in an atom = N = A – Z

EXPLANATION:​

• From the above, it is clear that the atomic mass of an element is equal to the sum of the number of protons and neutrons only. Therefore option 2 is correct.