as 2 moles of C r given and three of O₂ so after reaction with 2 moles of C reaction will stop leaving 2 moles of O₂ and 2 of CO₂. thats why it is 0,2,2
 i could not understand this line a bit. You say 2 moles of carbon react leaving 0 mole, which means it is fully used and out of 3 moles 1 moles completely react to give 2 mole oxygen. why have u written reaction with carbon not with oxygen. how to know carbon will be utilised fully.