Calculate the average mass number of copper on the basis of given information

cbse
structureofatom

#1

The relative abundance of two isotopic forms of copper viz. Calculate the average mass number of copper on the basis of given information.


#2

Average mass number = (Mass number ${}{63}^{29}Cu$ x 70 / 100) +
(Mass number ${}
{65}^{29}Cu$ x 30/100)
= 63x70/100 + 65 x 30 /100 = 63.6