The number of moles of oxygen in one litre of air containing 21% oxygen by volume under standard conditions is ′X′. What is the value of X ?
1000 mL of air at STP contains =21100 × 1000 = 210 mL O2
∴No.of moles=Vol. in mL under STP conditions22400 mL=21022400 = 0.009 mol
X=0.009
So, X×1000=9