If `10^(21)` molecules are removed from 200 mg of `CO_(2)`, the number of moles of `CO_(2)` left will be ?

Options

A. `2.88xx10^(-3)`
B. `1.66xx10^(-3)`
C. `2.54xx10^(-3)`
D. `1.66xx10^(-2)`

Answer

A

Explanation

`6.022xx10^(23)` molecules of `CO_(2)=1` mole `1xx10^(21)` molecules of `CO_(2)`
`=(1)/(6.022xx10^(23))xx1xx10^(21)=1.66xx10^(-3)` mole
44 g of `CO_(2)=1` mole
`200xx10^(-3)` g of `CO_(2)`
`=(1)/(44)xx200xx10^(-3)=4.54xx10^(-3)` mole
Moles of `CO_(2)` left =`4.54xx10^(-3)-1.66xx10^(-3)`
`=2.88xx10^(-3)`