Question

Calculate the atomic mass of element X if there are two isotopes of this element (X-24 and X-28) and 75% of all X atoms are X-28 isotopes.

52 amu


4 amu


27 amu


26 amu

Answer 1

Atomic mass = 27 amu

Step-by-step explanation:

Given data:

Atomic mass of element X= ?

Abundance of X-28 = 75%

Abundance of X-24 = 100 - 75 = 25%

Atomic mass of X-28 = 28 amu

Atomic mass of X-24 = 24 amu

Solution:

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

Average atomic mass = (75×28)+(25×24) /100

Average atomic mass = 2100 + 600 / 100

Average atomic mass = 2700 / 100

Average atomic mass = 27 amu.