A vessel of volume \(V=20\) l contains a mixture of hydrogen and helium at a temperature \(t=20{ }^{\circ} \mathrm{C}\) and pressure \(p=2.0\) atm. The mass of the mixture is equal to \(m=5.0 \mathrm{~g} .\) Find the ratio of the mass of hydrogen to that of helium in the given mixture.