Question

Assertion :The values of colligative properties are of smaller order as compared to values shown by true solutions at same concentrations. Reason: Colloidal particles show Brownian movement.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

Answer: (B)

• Colloidal particles being bigger aggregates, the number of particles in a colloidal solution is comparatively small as compared to a true solution.
• Hence, the values of colligative properties (osmotic pressure, lowering in vapour pressure, depression in freezing point and elevation in boiling point) are of small order as compared to values shown by true solutions at same concentrations.
  
• Colloidal particles show Brownian movement. The Brownian movement has been explained to be due to the unbalanced bombardment of the particles by the molecules of the dispersion medium.
• Hence, both assertion and reason are correct but the reason is not the correct explanation for the assertion.