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Chem problem that I can't remember how to do?

1. 4.0 moles of He(g) and 6.0 moles of N2(g0 exert a total pressure of 10 atm at 25 degrees C. What is the partial pressure of He(g)?

a) 0.4atm b) 6.0 atm c) 4.0 d) 0.6 atm e) 40 atm

This is probably very easy, I just can't remember as I learned it a long time ago.

So if you could explain how to do it so that I can do similar problems as well, that would be great. Thanks so much and 10 points to a best answer!4.0 mole He + 6.0 mole N2 = 10 moles
4.0 mole / 10 mole = mole fraction of He (= 0.40)
0.40 x 10 atm = 4 atm from He
6.0 mole / 10 mole = mole fraction of N2 (= 0.60)
0.60 x 10 atm = 6 atm from N2Answer is C..... B/C

The mole fraction of an individual gas component in an ideal gas mixture can be expressed in terms of the component's partial pressure or the moles of the component

xi =Pi/P = ni/n

and the partial pressure of an individual gas component in an ideal gas can be obtained using this expression:

Pi= xi *P

where:
xi = mole fraction of any individual gas component in a gas mixture

Pi = partial pressure of any individual gas component in a gas mixture

ni = moles of any individual gas component in a gas mixture

n = total moles of the gas mixture

P = pressure of the gas mixture