please refer image attached.
What is the mole fraction and partial pressure of Gas A in the container below if the measured pressure of the gases in the container is 935 mm Hg?
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molar fraction of Gas A==>4/16
partial pressure=(4/16)935=233.75 mm Hg

mole fraction of A = moles of A / total moles of gases
Now moles of A in container = 4
total moles of gases = 16
Partial pressure of A = mole fraction of A * P(total)
Partial pressure of A = 4/16 * 935 mm of Hg.