Question

how to calculate the number of moles present in 100g of Iron[II] oxide
if (Ar: Fe=56 , O=16

Answer 1

Iron[II]oxide means FeO
So here molecular mass of FeO = 56+16 =72

So in 100gm of FeO mole of Feo
$= weight \: of \: compound \: \div moleclar \: mass \: of \: compound$
$= (100) \div 72$
$= 1.39 \: mole$
So there are 1.39 mole of Feo
If you want to find individual mole than as in Feo are in ratio of 1:1 so there will be 1.39 mole of Fe and 1.39 mole of O so total of 2.78 mole of elements individually.