Answer:the initial composition of the reactants is
40cm^3 of CH4
40cm^3of H2
100cm^3 of H2O
Explanation:
Balanced reaction is
CH4 +H2+5/2O2______
CO2 +3H2O
Excess KOH at room temperature absorbs CO2 whose volume is given by 40cm^3 i.e the volume by which the solution decreases
So using Gay lussac combining ratio which states that gases combine in volumes that are in simple ratio to each other if gases.
Since CO2 in the equation is 1 mole
Means 1mole represent 40cm^3
So CH4:H2:O2 are in ratio of 1:1:5/2=(40:40:100)cm^3 respectively.