Question

which of the following is correct?
1. Two different solutions of urea of same molality will have same depression in freezing point.
2. Best method to calculate molar mass of biomolecule is via relative lowering of vapour pressure.
3. Decreasing order of osmotic pressure at the same temperature for 0.1M aqueous solution of BaCl2, KCl, and sucrose is BaCl2 >KCl >Sucrose
4. Vant Hoff factor of 0.1M Nacl and 0.1M CaCl2 aq.solution is same

Answer 1

The correct option from the following is:

(3) Decreasing order of osmotic pressure at the same temperature for 0.1 M aqueous solution of BaCl2, KCl, and sucrose is BaCl2 > KCl > Sucrose.

- Osmotic pressure is a colligative property, i.e., it depends upon the no of solute particles.

- In aqueous solution, BaCl2 dissociates to give 3 ions, KCl dissociates to give 2 ions and sucrose does not dissociate.

- Hence, at the same temperature and concentration, BaCl2 will have the largest and sucrose will have the lowest osmotic pressure.

- So, the correct answer is option (3).