Answer:
2.7E22 molecules  of SO2
Explanation:
Mole Fraction of N2 = 0.55
Mole Fraction of Ar = 0.25
Mole Fraction of SO2 = ?
The mole fraction of a molecule/compound = 1
But Mole fraction of compound = Mole fraction of SO2 + Mole fraction of Ar + Mole fraction of N2
Mole Fraction of SO2 = 1 - (0.55 + 0.25)
Mole Fraction of SO2 Â = 0.20
Total Number of moles of gas at STP in 5.0L
1 mol = 22.4L
x mol = 5L
X = 5 / 22 = 0.2232 mol
Number of moles of SO2 = Mole Fraction * Number of moles of gas
Number of moles of SO2 = 0.2232 * 0.20 = 0.0446 moles
Upon conversion to molecules;
1 mole = 6.022E23 molecules
0.0446 mole = x
x = 0.0446 mol * 6.022E23 molecule/mol = 2.7E22 molecules  of SO2