# If 10 raise to power 21 molecules are removed from 200 mg of CO2,then how many moles of CO2 are left?(Old and urgently dear experts)

Sep 26, 2016

$\text{Molar mass of "CO_2"=44g/"mol}$

"Amount of "CO_2 " taken"=200mg=(0.2g)/(44g/"mol")
$= 4.55 \times {10}^{-} 3 m o l$

$\text{Number of mlecules of "CO_2" removed} = {10}^{21}$

$\text{1 mol = "6.023xx10^23 "molecules of } C {O}_{2}$

${10}^{21} \text{ molecules } = {10}^{21} / \left(6.023 \times {10}^{23}\right) m o l$

$= 1.66 \times {10}^{-} 3 m o l$

$C {O}_{2} \text{ left} = \left(4.55 - 1.66\right) \times {10}^{-} 3 m o l$
$= 2.89 \times {10}^{-} 3 m o l$