When an excess of a very dilute aqueous solution of KI is addd to a very dilute aqueous solution of silver nitrate, the colloidal particles of silver iodide are associated with which of the following Helmholtz double layer ?

Options

A. `AgI//Ag^(+):I^(-1)`
B. `AgI//K^(+) : NO_(3)^(-)`
C. `AgI//NO_(3)^(-) : Ag^(+)`
D. `AgI//I^(-) : K^(+)`

Answer

D

Explanation

As excess of KI has been added, `I^(-)` ions are adsorbed on AgI forming a fixed layer (and giving it a negative charge). It then attracts the counter ions `(K^(+))` from the medium forming a second layer (diffused layer).