Chlorine has two stable isotopes,Cl-35 and Cl-37.If their exact masses are 34.9689 amu and 36.9695 amu,respectively,what is the natural abundance of Cl-35? (The atomic mass of chlorine is 35.45 amu.)
A)75.95%
B)24.05%
C)50.00%
D)35.00%
E)37.00%

Question

Quizplus · Accepted Answer

The natural abundance of the two isotopes can be represented as x and (1-x), where x is the abundance of Cl-35. We can set up a system of equations using the atomic mass of chlorine:

(34.9689 amu)(x) + (36.9695 amu)(1-x) = 35.45 amu

Simplifying and solving for x, we get:

x = 0.7595 or 75.95%

Therefore, the natural abundance of Cl-35 is 75.95%. The correct answer is choice A.

Chlorine Has Two Stable Isotopes,Cl-35 and Cl-37