8 liters of a mixture of C₂H₆ and C₃H₆ on complete combustion produces 21 liters of CO. Find the composition of the mixture.
a) 1:2 (C₂H₆:C₃H₆)
b) 2:1 (C₂H₆:C₃H₆)
c) 1:1 (C₂H₆:C₃H₆)
d) 3:1 (C₂H₆:C₃H₆)