Question

What is the average atomic mass of

the element in the data table?
Mass (amu)
Abundance (%)

0.3365
0.0632
99.60
[ ? ] amu

35.97
37.96
39.96

Answer 1

To find the average atomic mass, use the formula:
m1p1+m2p2+m3p3…
m is mass
p is percent (convert to decimal by dividing by 100)

So let’s put the numbers in:
(35.97)(0.003365)+(37.96)(0.000632)+(39.96)(0.996)
Now solve:
(0.12103905)+(0.02399072)+(39.80016)
39.94518977
That’s your average atomic mass.
The atomic mass is closest to Argon.