Question

Question #e76e2

Answer 1

If its 1.4% by mass, then that means there are `0.014*200.0=2.8mg` of the 214 isotope.

`2.8 mg=0.0028 g`

`0.0028/214=1.31*10^(-5) mol`
`2.8` mg of lead-214 is therefore `1.31*10^(-5)` mol

`1.31*10^(-5)*6.02*10^(23)=7.9*10^18` atoms
`1.31*10^(-5)` mol of a substance therefore contains `7.9*10^18` atoms.