List of top Chemistry Questions on Stoichiometry and Stoichiometric Calculations asked in AP EAPCET

One mole of $O_2$ (g) was passed over hot coke. At the end of the reaction, 40 % of $O_2$ (g) was unreacted. What is the volume (in L) of reaction mixture at STP (273.15 K and 1 bar)? (Assume only CO (g) is formed in the reaction)