The reaction involved in the explosion process isCO(g)+x mLCH4​( g)+y mL​21​O2​( g)⟶2x​ mL2O2​( g)⟶2y mL​CO2​( g)x mLCO2​( g)+2H2​O(l)y mL​The first step volume contraction can be calculated as :(x+2x​+y+2y)−(x+y)=13x+4y=26​The second volume contraction is due to absorption of CO2​.Hence, x+y=14Now, solving equations (i) and (ii), x=10 mL,y=4 mL and volume of He=20−14=6 mL ⇒Vol% of CO=2010​×100=50%Vol% of CH4​=204​×100=20% Vol% of He=30%