I don't understand this :c
help me please

8) a mixture of he, ne and ar has a pressure of 7.85 atm. if the ne has a mole fraction of 0.47 and 8) ar has a mole fraction of 0.23, what is the pressure of he? a) 4.2 atm b) 3.7 atm c) 5.5 atm d) 2.4 atm e) 1.8 atm

Amixture with the same composition throughout is!

How many moles of no2 will form when 3.3 moles of cu are reacted with excess hno3?