Question

1. the atomic mass of an element is in fraction. what does it mean?

Answer 1

an element if contains isotopes i.e. atoms of the same elements with different numbers of neutron then it becomes difficult to choose the atomic mass from those available isotopes.
So we take the average of atomic masses of all the available isotopes... and hence mass no. comes in fraction.
Thank u

Answer 2

your answer

if atomic mass is in fraction this means that the number of neutrons are different this is is the case of isotope when neutron is different so we know that atomic mass is neutron + protons so it may come in fraction

hope helps