How to tell , whether a colloidal solution is positively or negatively charged??
Dear Harry, the best way to check whether the colloidal solution is positively charged or negatively charged is the process of Electrophoresis.
And one another method is Coagulation.
Dear Harry this topic belongs to the surface chemistry, for more clarification goes through the NCERT book of 12th or you can refer online source like youtube.
All the best dear