Partial Pressure

Step 1: Understanding Raoult's Law
Raoult's Law states that the vapour pressure of a solution ( ) is given by: where: - is the vapour pressure of the pure solvent. - is the mole fraction of the solvent.

Step 2: Calculating the Mole Fraction of the Solvent
Given: - Moles of solute = 0.1 - Moles of solvent = 0.9 - Vapour pressure of pure solvent = 0.9 Total moles in the solution: Mole fraction of the solvent:

Step 3: Calculating the Vapour Pressure of the Solution
Applying Raoult's Law:

Step 4: Evaluating the Given Options
- Option (1): Incorrect, as is too high.
- Option (2): Correct, as calculated .
- Option (3): Incorrect, as is not accurate.
- Option (4): Incorrect, as is too low.
Thus, the correct answer is

Option (2).

Step 1: Understanding Boiling Point Trends in Hydrogen Halides
The boiling point of a compound is influenced by intermolecular forces, including: - Van der Waals forces: Increase with molecular size. - Hydrogen bonding: Strongest in HF due to high electronegativity of fluorine.

Step 2: Analyzing the Boiling Points
1. **Hydrogen Fluoride (HF):** Exhibits strong hydrogen bonding, leading to an exceptionally high boiling point. 2. **Hydrogen Chloride (HCl), Hydrogen Bromide (HBr), and Hydrogen Iodide (HI):** These molecules experience only Van der Waals forces, which increase with molecular mass. Since iodine is the largest halogen, HI has the weakest Van der Waals forces among them, leading to the lowest boiling point, followed by HBr, then HCl.

Step 3: Establishing the Order
From experimental data, the boiling points of hydrogen halides follow the order:

Step 4: Conclusion
Thus, the correct order of boiling points is: