Question 14 On Mars, the element zircon has two isotopes, Zr156 and Zr160.84% of a sample is Zr156, which has an atomic mass of 156.8 amu, and 16% Zr160, which has an atomic mass of 159.4 amu. What is the average atomic mass of zircon on Mars? 157.2 amu 158.0 amu 159.2 amu 162.4 amu

Option A is correct = 157.2 amu

Explanation:

Given data:

Percentage abundance of Zr-156 = 84%

Atomic mass of Zr-156 = 156.8 amu

Percentage abundance of Zr-160 = 16%

Atomic mass of Zr-160 = 159.4 amu

Average atomic of Zr on Mars = ?

Solution:

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass = (84×156.8)+(16×159.4) /100

Average atomic mass =  13171.2 + 2550.4  / 100

Average atomic mass  = 15721.6 / 100

Average atomic mass = 157.2 amu.