Question

Copper occurs naturally as Cu-63 and Cu-65. Which isotope is more abundant?

A) Cu-63 is more abundant because it has a lower mass.
B) Cu-65 is more abundant because it has a higher mass.
C) Cu-63 and Cu-65 are equally abundant.
D) The abundance of isotopes is unrelated to their mass.

Answer 1

Cu-63 with an abundance of 69.09% is more abundant than Cu-65. The abundance of an isotope is related to its natural prevalence rather than its mass.

Step-by-step explanation:

The question asks which isotope of copper occurs more abundantly in nature, Cu-63 or Cu-65. Copper has two stable isotopes, Cu-63 with a mass of 62.929595 g/mol and Cu-65 with a mass of 64.927786 g/mol. According to the data provided, Cu-63 has an abundance of 69.09%, while Cu-65 has an abundance of 30.91%. Therefore, the correct answer is A) Cu-63 is more abundant because it has a lower mass; however, the primary reason it's more abundant is its natural prevalence, not its mass. This coincides with the abundance principle observed for other elements, where one isotope is often more abundant than the others regardless of mass.