Answer:
73.988 amu
Explanation:
Given data:
Abundance of 1st isotope = 38.92%
Abundance of 2nd isotope = 61.08%
Atomic mass of 1st isotope = 73.942 amu
Atomic mass of 2nd isotope = ?
Average atomic mass = 73.970 amu
Solution:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) / 100
73.970 = (38.92×73.942)+(61.08×atomic mass) /100
73.970 ×100 = 2877.823 + (61.08×atomic mass)
7397 = 2877.823 + (61.08×atomic mass)
7397 -2877.823 = (61.08×atomic mass)
4519.18 = 61.08×atomic mass
4519.18 / 61.08 = atomic mass
73.988 amu = atomic mass