Question

the mass number of an atom is slightly less than the atomic number give reason

Answer 1

Because they are isotopes


Mass no. = Protons +neutrons

For example =H
Atomic no. =1
Mass no. =1
Because it has only 1 proton but no neutrons.


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Answer 2

Answer:

Because they are isotopes

Mass no. = Protons +neutrons  

For example =H

Atomic no. =1

Mass no. =1

Because it has only 1 proton but no neutrons.