Answer:

X He = 0.588

X N₂ = 0.353

X Ar = 0.059

P He = 5.88 atm

Explanation:

Calculating the number of moles of each gas

n He = 20 g × (1 mol / 4 g) = 5 mol

n N₂ = 84 g × (1 mol / 28 g) = 3 mol

n Ar = 20 g × (1 mol / 40 g) = 0.5 mol

Calculating the total number of moles

n_T = n He + n N₂ + n Ar

n_T = 5 mol + 3 mol + 0.5 mol

n_T = 8.5 mol

Calculating the mole fraction of each gas

For He

X He = n He / n_T

X He = 5 mol / 8.5 mol

X He = 0.588

For N₂

X N₂ = n N₂ / n_T

X N₂ = 3 mol / 8.5 mol

X N₂ = 0.353

For Ar

X Ar = n Ar / n_T

X Ar = 0.5 mol / 8.5 mol

X Ar = 0.059

Calculating the partial pressure of He

P He = (X He)(P_T)

P He = (0.588)(10 atm)

P He = 5.88 atm

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