Question

give reason:- Sum of the numbers of protons and neutrons is the atomic mass, where no. of electrons are not
included​

Answer 1

Explanation:

The atomic number of an atom is the number of protons it contains. All the atoms of a particular element have the same atomic number (number of protons). The atoms of different elements have different numbers of protons. For example, all oxygen atoms have 8 protons and all sodium atoms have 11 protons. The mass number of an atom is the total number of protons and neutrons it contains. The mass number of an atom is never smaller than the atomic number.

Answer 2

Answer:

1) The mass of the atom is all concentrated in the nucleus just like a centre of mass.

2) Electrons have negligible mass