Anyone up to give me hint on how to do this?

A 5.00-L vessel at 25 Celcius contains He and H2.
The partial pressure of He is 0.50 atm and the partial pressure of H2 is 1.50 atm.
The mole fraction of He is equal to:

Question

Anyone up to give me hint on how to do this?

A 5.00-L vessel at 25 Celcius contains He and H2. 
The partial pressure of He is 0.50 atm and the partial pressure of H2 is 1.50 atm. 
The mole fraction of He is equal to:

jfraser · Answer

since the pressure of a gas is directly proportional to the number of moles of each gas, the mole fraction will be equal to the pressure fraction as well