what volume of carbon dioxide is formed when 11 of CS2 reacts with 18 L O2 to produce carbon dioxide gas and sulfur dioxide gas at STP?

Answer 1

This is a limiting reagent problem. You know that because you have amounts given for BOTH reactants.
CS2 + 3O2 ==> CO2 + 2SO2
Is that 11 L CS2? If so you can take a shortcut and not convert L to mols but use L directly. As follows:
L CO2 formed will be
L CS2 x (1 mol CO2/1 mol CS2) = 11 x (1/1) = 11 L CO2 (If we had all of the O2 we needed.

If we had 18 L O2 the volume of CO2 formed will be
L O2 x (1 mol CO2/3 mols O2) = 18 x (1/3) = 6 L CO2 (if we had all of the CS2 need).
You get two different answers this way which means one of them is wrong; the correct answer in limiting reagent problems is ALWAYS the smaller value; therefore, 6L CO2 will be the volume of CO2 formed at STP.