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According to Raoult's law, the relative lowering in vapour pressure of dilute solution is equal to the mole fraction of the solute present in the solution. p° - p / p° = mole fraction of solute = n / n + N.

1. p° - p / p° = mole fraction of solute
2. n / n + N
3. For ideal solution, ΔHmixing = 0 and ΔHmixing = 0.
4. Ethyl alcohol forms hydrogen bonding with itself, hence it will not form ideal solution with C2H5I.

Correct answer: p° - p / p° = mole fraction of solute

Solution

Raoult's law states that the relative lowering of vapor pressure is directly proportional to the mole fraction of the solute.

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