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Answer» 1mg = 10^-3 g then ,
200mg = 200×10^-3g _________________________ 1 MOLE of NO2 CONTAINS = (14×2)+(16) = 44g/mol
then " y moles contains = 200mg = 200×10^-3g
y = 200×10^3/44
y = 4.55 × 10^-3 moles
then ,
4.55 × 10^-3 - X = 2.89 × 10^-3
- X = (2.89 × 10^-3) - (4.55 × 10^-3)
- X = -1.66 × 10^-3
X = 1.66 × 10^-3 ___________________________________________ molar mass:- mass of the one mol of the SUBSTANCE is called molar mass
onother method
mass = number of moles × molar mass
200mg = number of moles × 44g/mol
number of moles = 200×10^-3/44
number of moles = 4.55 × 10^-3 moles
so 200mg of N2O contains 4.55 × 10^-3
therefore ,
4.55 × 10^-3 - X = 2.89 × 10^-3
- X = -1.66 × 10^-3
X = 1.66 × 10^-3
so your answer is 1.66 × 10^-3
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