Question

chemical property of an element is determined by atomic mass number and atomic mass give reason

Answer 1

chemical property of an element is determined by the atomic number i.e. the number of protons as atomic number doesn't varies it is fixed and mass number varies ...so , chemical property of an element is determined by the number of protons present in it .
hmm...but quite a little doubt ! oops ....
 
i hope it helps..........