A colloidal solution of `Agl` is prepared by two different methods as shown in the figure below:


What is the charge of `Agl` colloidal particles in the two test tubes `(A)` and `(B)` ?
b. Given reasons for the origin of charge.

Explanation

a. Test-tube (A) has negative charge whereas test tube (B) has positive charge on the colloidal particles.
b. In test tube (A), `I^(ɵ)` is adsorbed on precipitate `Agl` [or `Agl//I^(ɵ)` is formed]. In test tube (B), `Ag^(o+)` is adsorbed on precipitate `Agl` [or `Agl//Ag^(o+)` is formed].