partial pressure?

Question

1. A mixture of helium and neon gases is collected over water at 28.0 °C and 745 mmHg. If the partial pressure of helium is 368 mmHg, what is the partial pressure of neon? (Vapor pressure of water at 28 °C = 28.3 mmHg.)


Dry air near sea level has the following composition by volume: N2, 78.08 percent; O2, 20.94 percent; Ar, 0.93 percent; CO2, 0.05 percent. The atmospheric pressure is 1.00 atm.


Calculate the partial pressure of each gas in atm.
a Partial pressures: N2 =0.781 atm; O2 = 0.209 atm; Ar = 9.3 × 10-3 atm; CO2 = 5 × 10-4 atm
b Partial pressures: N2 =78.1 atm; O2 = 20.9 atm; Ar = 0.93 atm; CO2 = 0.05 atm
c Partial pressures: N2 =78.1 atm; O2 = 20.9 atm; Ar = 9.3 × 10-3 atm; CO2 = 5 × 10-4 atm
d Partial pressures: N2 =0.0781 atm; O2 = 0.0209 atm; Ar = 9.3 × 10-4 atm; CO2 = 5 × 10-5 atm

Answer 1

Are you asking this just for fun/ joking?

Based on the DEFINITION of partial pressure:
1. the partial pressure of neon must be: (745 -368 - 28.3) mmHg

2. So all partial pressures must be added together to get 1 atm: (a) is the only correct answer.