Equal masses of he and ne are placed in a sealed container. What is the partial pressure of he if the total pressure in the container is 6 atm?

6 atm.

Explanation:

Let the mass of both be m

Then moles of He = m / 4

Moles of Ne = m / 20

mole fraction of He = Moles of He / Total moles = m/4 / (m/4 + m/20) = 0.25 m/0.3m = 0.83

Pressure of He = Mole fraction*total pressure = 0.83 * 6 atm = 5 atm