Amixture of neon and oxygen gases in a balloon exerted a pressure of 2.008 atm, given that there were 4.45 g neon gas and 3.45 g of oxygen gas in the balloon, calculate the partial pressure of oxygen gas.

Partial pressure is the pressure exerted by individual gases.
Partial pressure of a gas is the product of the mole fraction of that gas by the total pressure 
total pressure of the mixture is 2.008 atm
number of moles of Ne gas - 4.45 g / 20 g/mol = 0.222 mol
number of moles of O₂ gas - 3.45 g / 32 g/mol = 0.108 mol
total number of moles in the mixture = 0.222 + 0.108 = 0.330 mol
Mole fraction of O₂ = number of moles of O₂ / total number of moles 
                               = 0.108 mol / 0.330 
 mole fraction of O₂ = 0.327 
partial pressure of O₂ = 0.327 x 2.008 atm = 0.657 atm 
partial pressure of O₂ is 0.657 atm 

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