If `10^(23)` molecules are removed from 200 mg of `CO_2`, the number of moles of `CO_2` left are

Options

A. `2.88 xx 10^(-3) `
B. `28.8 xx 10^(-3)`
C. `0.288 xx 10^(-3)`
D. `1.66 xx 10^(-2)`

Answer

A

Explanation

200 mg `CO_2 = 0.2 g = (0.2)/(44 )` mol
`= 0.00454 mol = 4.54 xx 10^(-3)` mol
` 10^(21)` molecules of ` CO_2 = ( 10^(21))/( 6.02 xx 10^(23))=1.66 xx 10^(-3)` mol
` therefore ` No . Of moles lefr ` = ( 4.54 -1.66 ) xx 10^(-3) = 2.88 xx 10^(-3)`