On adding ${\mathrm{AgNO}}_3$ solution to $\mathrm{KI}$ solution, a negatively charged colloidal sol will be formed in which of the following conditions?

 When ${\mathrm{AgNO}}_3$ completely precipitates as Agl and additional KI is absorbed on Agl , a negatively charged colloidal sol is created. 

$$\begin{gathered} {\mathrm{Ag}}^{+}+{\mathrm{I}}^{-}\to \mathrm{Agl} \\ \mathrm{AgI}+{\mathrm{I}}^{-}\to [\mathrm{Ag}1{]}^{-} \\ \text{Thus, }\left[{\mathrm{Ag}}^{+}\right]<\left[{\mathrm{I}}^{-}\right] \end{gathered}$$

Hence the correct option is (B).