The balanced chemical reaction is given as:
2H2S (g) + 3O2 (g) 2SO2 (g) + 2H2O (g)
We are given the volume at STP of H2S to be used for the reaction. This would be the starting point for the calculations. We do as follows:
45.0 L H2S ( 1 mol / 22.4 L) ( 3 mol O2 / 2 mol H2S ) ( 22.4 L / 1 mol ) = 67.5 L O2 needed
Please mark as Brainliest