The normal condition of the mole of a gas is 22.44L.
The volume of CH4 = 8.9L
To get the number of moles we get,
8.9 / 22.44 = 0.397 moles.
The ratio of CH4 : H2O = 1: 2
The mole of water is 0.379 × 2 = 0.794 moles.
While we convert it into liters it will be
0.794 × 22.414 = 17.80L
The answer is 17.80 liters of water vapour which will be produced.