Colligative Properties

Step 1: Raoult's Law
Relative lowering of vapour pressure ( ) is equal to the mole fraction of the solute ( ).
Step 2: Values
.
For a dilute solution, , so .
Step 3: Molality Formula
.
Step 4: Calculation
Using : .
Final Answer: (A)

Step 1: Formula
Osmotic pressure . It is a colligative property depending on the number of particles ( ).
Step 2: Particle Analysis
- Urea: (non-electrolyte)
- Glucose: (non-electrolyte)
- KCl: ( )
- : ( )
Step 3: Conclusion
produces the maximum number of ions, hence the highest osmotic pressure.
Final Answer: (D)

Step 1: Understanding the Concept:
Molal depression constant .

Step 2: Detailed Explanation:
K.
J/g.
J/K·mol.
.

Step 3: Final Answer:
3.86

Step 1: Understanding the Concept:
The van't Hoff factor (i) is the ratio of the number of particles after association/dissociation to the number of particles before.

Step 2: Detailed Explanation:
Benzoic acid in benzene undergoes dimerization due to intermolecular hydrogen bonding. Initially, 2 molecules. After complete dimerization, they form 1 molecule. So, the van't Hoff factor .

Step 3: Final Answer:
The van't Hoff factor is 0.5, which corresponds to option (C).