A certain element is composed of two isotopes,having the mass and abundance shown in the table.What is the average atomic mass for this element? Mass
Abundance
Isotope 1
35.0 u
75.8%
Isotope 2
37.0 u
24.2%

Question

Quizplus · Accepted Answer

To find the average atomic mass of this element, we need to use the formula:

average atomic mass = (mass of isotope 1 x abundance of isotope 1) + (mass of isotope 2 x abundance of isotope 2)

In this case, plugging in the values gives us:

average atomic mass = (35.0 u x 0.758) + (37.0 u x 0.242)
average atomic mass = 26.53 + 8.95
average atomic mass = 35.48 u

Therefore, the best choice is B) 35.5 u, which is the closest answer to 35.48 u (rounded to one decimal place).

A Certain Element Is Composed of Two Isotopes,having the Mass