Question

Give reason :-
◆Mass no. is slightly less than the actual atomic mass.

Answer 1

Answer:

mass number =sum of protons and neutrons in the atom.

atomic number is the number of protons only

so there is slight difference in the mass number than actual atomic mass.

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Answer 2

Answer

The mass number is not equal to the atomic mass because of isotopes.

Mass number is simply the number of protons and neutrons.

The actual atomic mass of an atom is the weighted average of all existing atoms & isotopes per element. The isotopes have a different number of neutrons than protons.