a sample of water gas has a composition by volume of 50 % hydrogen 45 % carbon monoxide and 5 %carbon dioxide. calculate the volume in litres at STP of water gas which on treatment with excess of steam will produce 5 litre hydrogen .the equation for the reaction is co + H2O -> CO2 + H2

Let us use 'x' litre of water gas at STP. So it has 0.5x litre of H₂     (∵∵ H₂ = 50%) 

Now from CO  +  H₂O   ⟶⟶    CO₂         +     H₂

to              0.45x excess          0.05x            0.5x

t                 0        –         (0.05x+0.45x) (0.5x+0.45x) (0.05x+0.45x) (0.5x+0.45x) 

So total vol. of  H2= 0.95 x H2 = 0.95x

but according to question it is 5 litre.

hence 0.95x = 5

 ∴x = 5.263litre