Question

write a balanced equation for the reaction : if 40cm3 of Carbon (2) oxide were mixed with 30cm3 of oxygen : calculate the volume of Carbon(4) oxide gas produced

Answer 1

A picky point. To show oxidation state you should use Roman numbers; i.e., Carbon(II) oxide for CO and carbon(IV) oxide for CO2. That may not be much to you but you should learn to do it right.
................2CO + O2 ==> 2CO2
Initital.......40 cc..30 cc.........0 cc
First, what is the limiting reagent? If all 40 cc CO react how much O2 will be needed? That's 40 cc x 1/2 = 20 cc O2. You have that much; therefore, ALL of the CO will be used (that is CO is the limiting reagent) which means that 40 cc CO will be produced.