Answer:
0.000399316 g
Explanation:
We can start with the <u>molar fraction</u> for each isotope:
We can say that the abudandance of
is an unknow value <u>"X"</u> and the molar fraction of
is <u>"Y"</u>. We have to keep in mind that the molar fractions can be added:
Y + X = 1
So, we can put the molar fraction of
in terms of
, so:
Y=1-X
So, we will have the <u>molar fraction of each isotope</u>:
: X-1
: X
And the <u>atomic mass</u>:
: 21.9944
: 22.9898
If we multiply the molar mass by the each atomic mass of each isotope we will have:

Now we can solve for "X" :






The molar fraction of
is <u>0.999749</u>. Now we can calculate the molar fraction of
, so:

Now, if we multiply the molar fraction by the mass we can find the <u>mass</u> of
, so:

The mass of
is 0.000399316 g
I hope it helps!