Ncert Exercises & Solutions

Select the correct option based on statements below:

Assertion (A):	The coagulation power of Al³⁺ is more than Na⁺.
Reason (R):	Greater the valency of the flocculating ion added, the greater is its power to cause precipitation (Hardy-Schulze rule)

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.	(A) is true but (R) is false.
4.	(A) is false but (R) is true.

Hint: Coagulating power

\propto

charge/valency of flocculating ion

Explanation:

The greater the charge/ valency of the flocculating ion added, the greater is its power to cause precipitation.

This is known as the Hardy-Schulze rule. In the coagulation of a negative

sol, the flocculating power is in the order: Al³⁺>Ba²⁺>Na⁺