Answer:
H₂: 0.48, N₂: 0.43; Ar: 0.09
Explanation:
First of all, sum all the pressures to know the total pressure in the mixture.
434 Torr + 389.9 Torr + 77.9 Torr = 901.8 Torr
Mole fraction = Pressure gas / Total Pressure
Mole Fraction H₂: 434 Torr /901.8 Torr = 0.48
Mole Fraction N₂: 389.9 /901.8 Torr =0.43
Mole Fraction Ar: 77.9 /901.8 Torr = 0.09
Remember: SUM OF MOLE FRACTION = 1