Carbon occur in nature as a mixture of `C-12` and `C-13`. Average atomic mass of carbon is `12.011` what is the `%` abundance of `C-12` in nature ?

Options

A. `98.9%`
B. `60.9%`
C. `32.9%`
D. `1.4%`

Answer

1

Explanation

`{:("Isotopes of carbon",,C^(12),,C^(13)),(% " of abundance",=,x%,,(100-x)%):}`
Average atomic mass `=(x xx12)/(100)+((100-x)xx13)/(100)`
`12.011=(12x)/(100)+(1300-13x)/(100)`
`12.011=(12x+1300-13x)/(100)=(-x+1300)/(100)`
`12.011=(-x+1300)/(100)`
`-x+1300=1201.1`
`-x=12.011-1300`
`-x=-98.9`
`x=98.9%`
`:. C^(12)=98.9%`
`C^(13)=1.1%`