Question

why mass number is equal to be the number of protons plus neutrons.? ​

Answer 1

Answer:

humko nhi aata hai agar aata to jaruur batate yrr

Answer 2

Answer:

Atomic Mass is equal to the sum of no. of protons to the no. of neutrons .

We know that the fundamental particles of an atom are electrons , protons and neutrons . And we also know that protons and neutrons are in the nucleus of the atom and electrons revolves around the nucleus of the atom .

The proton have a mass of 1.6727 x 10^-24 g

The neutron have a mass of 1.6 x 10^-24 g

The electron has a mass of 9.1 x 10^-28 g

Here , we can see that the mass of the electron is approximately neglegible in comparison with neutron and proton . And that’s why we also say that the mass of the atom is constituted of its nucleus .

And the neglegible small mass of the electron is the reason that atomic mass is equal the no. of protons plus no. of neutrons .