Could hydrogen be collected by the displacement of water?
That’s the best way to collect Hydrogen. As it’s lighter than air, when passed underwater, into an inverted, water filled test tube, the water in the tube will be displaced downwards filling the tube with H2. The tube can then have a stopper inserted while still inverted and under water, then the gas can be taken for analysis. H2 is not soluble in water except under high pressure but, it will escape again when the pressure is released.
