Question

Element “X” is a brand new element. Scientists discovered that 80% of the atoms of element

“X” have a mass number of 10 amu and the other 20% have a mass of 11 amu. What is the avg.
atomic mass of element "X"?

Answer 1

Average atomic mass of X is 10.2 amu.

Step-by-step explanation:

Given data:

Percentage abundance of X-10 = 80%

Percentage abundance of X-11 = 20%

Average atomic mass of X = ?

Solution:

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

Average atomic mass of \X = (80×10)+(20×11) /100

Average atomic mass of X = 800 + 220 / 100

Average atomic mass of \X = 1020 / 100

Average atomic mass of X = 10.2 amu