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SAT® Subject Test in Chemistry

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Calculating Average Atomic Mass

SATCHM-3TV61Q

An element $(X)$ has two naturally occurring isotopes. $X-90$ has an abundance of $75\%$ and $X-94$ has an abundance of $25\%$.

What is the average atomic mass of element $X$?

A

$90 \ amu$

B

$91 \ amu$

C

$92 \ amu$

D

$93 \ amu$

E

$94 \ amu$