Air is a mixture of 21% oxygen gas and 79% nitrogen gas. Calculate the average molar mass of a mixture of air. I’m very lost, I thought I was supposed to use mole fraction but it does not get me anywhere, due to not having the total amount of moles. Maybe it has to do with finding pressure?
Here are formulas that I know of:
MM = DRT/P
- MM is molar mass
- D is density
- R is ideal gas constant
- T is temperature in Kelvin
- P is pressure
PV = nRT
- V is volume
- n is moles
Please help, thank you.

In which of these cases are the two wave points considered to be in phase with each other?

Select the correct answer. when carbon dioxide dissolves in water, it sometimes reacts with water to form carbonic acid as in this balanced equation: co2 + h2o → h2co3. if 495 milliliters of carbon dioxide at 25°c and 101.3 kilopascals reacts with excess water, what is the theoretical yield of carbonic acid? use the periodic table and the ideal gas resource a. 0.889 g b. 1.10g c. 1.27g d. 2.02g what's the answer! quick!

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