A vessel of volume \(20\,\text{L}\) contains a mixture of hydrogen and helium at temperature \(27^\circ\text{C}\) and pressure \(2\,\text{atm}\). The mass of the mixture is \(5\,\text{g}\). Assuming the gases to be ideal, the ratio of mass of hydrogen to that of helium in the mixture is:
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For gas mixtures:
\[
n=\sum \frac{m}{M}
\]
Use molecular masses carefully.