a sample of chlorine gas is confined in a 3.0-L container at 542 torr and 37 C. how many moles of gas are in the sample? (please help me)

Consider this reaction taking place in a closed 2 liter container: 2so2(g) + o2(g) → 2so3(g) if the volume of the container is decreased to 1 liter, what will happen to the equilibrium of the reaction? it will shift left. it will shift right. it will remain constant it will decrease by half