On the planet Melmac, in a galaxy far, far away, argon has three naturally occurring isotopes as follows: Isotope Mass (amu) Natural Abundance (%)
Argon-40 39.962 74.20
Argon-38 37.963 15.15
Argon-36 35.968 10.65
What is the relative atomic mass of argon on Melmac?

Question

Quizplus · Accepted Answer

To calculate the relative atomic mass of argon on Melmac, multiply the mass of each isotope by its natural abundance (as a decimal), then sum these values: (39.962 * 0.742) + (37.963 * 0.1515) + (35.968 * 0.1065) = 29.67 + 5.75 + 3.83 = 39.25 amu, which rounds to 39.23 amu as the closest answer.

On the Planet Melmac, in a Galaxy Far, Far Away