Question

Which from following process does NOT results in coagulation?

• A. electrophoresis
• B. by adding excess solvent
• C. by mixing two oppositely charged sols
• D. by boiling

Hint:

Coagulation means the colloidal particles lose their charge and settle; check what each process does to the charge or stability of the sol.

Answer 1

The Correct Option is B

Step 1: Ways to Coagulate a Sol
A sol is coagulated by adding an electrolyte, by mixing oppositely charged sols, by electrophoresis, or by boiling.

Step 2: Apply to the Options
Electrophoresis, mixing oppositely charged sols and boiling are all in this list.

Step 3: Compare the options
Adding excess solvent merely dilutes the sol, so it is the one that does not cause coagulation.

Final Answer:
Only adding excess solvent fails to coagulate the sol. \[ \boxed{\text{(B) }\text{by adding excess solvent}} \]