If `10^(21)` molecules are removed from 100mg `CO_(2)`. Then number of moles of `CO_(2)` left are:

Options

A. `6.10xx10^(-4)`
B. `2.8xx10^(-3)`
C. `2.28xx10^(-3)`
D. `1.36xx10^(-2)`

Answer

A

Explanation

Number of molecules in 100 mg `CO_(2)`
`=("Mass ")/("Molar mass")xx6.023xx10^(23)`
`=(0.1)/(44)xx6.023xx10^(23)`
`=1.368xx10^(21)`
Molecules remaining `=1.368xx10^(21)-10^(21)=0.368xx10^(21)`
Number of moles remaining `=(0.368xx10^(21))/(6.023)xx10^(23)=6.1xx10^(-4)`