on igniting a mixture of c2h2 and o2,200cc of co2 is formed.calculate the volume of c2h2 and o2 in the original mixture
This looks like a pure de ol' stoichiometry problem to me.
2C2H2 + 5O2 ==> 4CO2 + 2H2O
By using volumes directly as if they were mols, a short cut can be used which cuts out a couple of steps. I suppose we assume that C2H2 and O2 are there is proportional amounts and neither is in excess.
200 cc CO2 x (2 mols C2H2/4 mols CO2) =? cc C2H2.
200 cc CO2 x (5 mols O2 x 4 mols CO2) = ?