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

Options

A. `2.88 xx 10^(-3)`
B. `1.66 xx 10^(-3)`
C. `4.54 xx 10^(-3)`
D. `1.66 xx 10^(-2)`

Answer

A

Explanation

No. of molecules in 200 mg of `CO_(2)`
`= (6.022 xx 10^(23))/(44)xx0.2=2.73xx10^(21)`
No. of molecules removed `= 10^(21)`
No. of molecule left
`= (27.73 xx 10^(21) - 1 xx 10^(21))`
`= 1.73 xx 10^(21)` molecules
No. of moles left`= (1.73xx10^(21))/(6.022xx10^(23))`
`=2.87xx10^(-3)`