77.2 L of So2= moles of SO2

Question

any way 

Answer 1

One must assume that the 77.2 L of SO₂ gas is at STP (1 atm and 273K), otherwise there isn't enough info to calculate the moles.  At STP 1 mole of an ideal gas = 22.4 L, thus...

77.2 L x 1 mol/22.4 L = 3.45 moles of SO₂