`SnO_(2)` form a positively charged colloidal sol in the acidic medium and negatively charged sol in the basic medium. Explain.

Explanation

`SnO_(2)` is of amphoteric in natrure which means that it can react with both acids and beses. With an acid such as HCl, it from `SnCl_(4).` The `Sn^(4+)` ion are adsorbed on the surface of `SnO_(2)` to give a positively charged colloidal sol.
`SnO_(2)+4Hcl to SnCl_(4)+2H_(2)O`
`SnO_(2)+Sn^(4+) to underset("positively charged sol")([SnO_(2)]Sn^(4+))`
Similarly with base like NaOH, it froms sodium stannate `(Na_(2)SnO_(3)).` The stannate ions get adsorbed on the surface of `SnO_(2)` to give positively charged colloidal sol.
`SnO_(2)+2NaOH to Na_(2)SnO_(3)`
`SnO_(2)+SnO_(3)^(2-) to underset("negitively charged sol") ([SnO_(2)]SnO_(3)^(2-))`