Water is a cheap, easy shield and can be used for drinking and temperature moderation. There would also be some shielding effect from the oxygen but I don't know how much. A cubic meter of water weighs 1,000 kilograms. Divided by atomic weight of water of .018 kg/mole we get 55,555 moles.
The equivalent amount of gaseous hydrogen (55,555 moles) put into a one cubic meter bottle and held at room temperature (293 K) will have a pressure = n R T = 55,555 x 8.3 x 293 = 1.35e8 Pascals which is 1336 atm or 19,600 psi. This is not a good option as a radiation shield for a human habitat.
Liquid hydrogen weighs 70 grams per liter so a cubic meter would be 70 kg, which is 70,000 moles. This would be 26% better as a shield but in order to contain it at a modest 15 psi, it would need to be chilled to 20 Kelvins. Perhaps in outer space with a 3 K background this might not be a problem. There would need to be around 10 meters of liquid outside the living area, which should be at least 10 meters in diameter, so the diameter would be around 30 meters. For a 30 meter diameter steel tank at 15 PSI the skin would only need to be about 1/8" thick. I think the biggest problem would be living inside such a cold liquid. There would have to be quite a bit of insulation, probably around a meter.