An element has three stable isotopes with masses of 27.977 amu, 28.976 amu, and 29.973 amu. The heavier two isotopes have an abundance of 4.68% and 3.09%, respectively. What is the mass of the element? A) 29.251

B) 27.684

C) 28.085

D) 28.991

E) 30.107

The mass of the element is 28.085 amu

Explanation:

Step 1: Data given

Masses of isotopes:

27.977 amu ⇒

28.976 amu ⇒ 4.68%

29.973 amu ⇒ 3.09%

Step 2: Calculate the abundance of the other isotope

100% - 4.68% - 3.09 % = 92.23 %

Step 3: calculate the mass othe element

0.9223 * 27.977 + 0.0468 * 28.976 + 0.0309*29.973 = total mass of the element

Total mass of the element = 28.085 amuj

The mass of the element is 28.085 amu