What is the percentage of people that say they use at least one prescription drug per month?

Is this a single replacement reaction or there is no

0.09 moles of sodium sulfate in 12 ml of solution

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