The three naturally occurring isotopes of magnesium are 24Mg (23.985042 u, 78.99%), 25Mg (24.985837, 10.00%), and 26Mg. What is the atomic mass of 26Mg?
A) 25.98 u
B) 48.67 u
C) 23.94 u
D) 26.43 u
E) 24.31 u

Question

Quizplus · Accepted Answer

The atomic mass of magnesium is calculated using the weighted average of its isotopes. Given the atomic masses and abundances of 24Mg and 25Mg, the atomic mass of 26Mg can be deduced to be approximately 25.98 u to match the average atomic mass of magnesium, which is about 24.31 u.

The Three Naturally Occurring Isotopes of Magnesium Are 24Mg (23