Question

$AgCl$ is white while $AgI$ is yellow, this is because:

• A. $A{g}^{+}$ has 18 electron shell to screen the nuclear charge
• B. $A{g}^{+}$ shows pseudo inert gas configuration
• C. Distortion of $I^{-}$ is more pronounced than $C{l}^{-}$ ion
• D. Distortion of $A{g}^{+}$ ion is more in case of $AgI$

Answer 1

The correct option is C Distortion of $I^{-}$ is more pronounced than $C{l}^{-}$ ion

The electronic configuration of $A{g}^{+}$ is $\left[Ar\right]3d^{10}4s^{2}4p^{6}4d^{10}$.
So, it has 18 electrons in the valence shell. Thus, $A{g}^{+}$ shows pseudo inert gas configuration. But this does not explain the reason of $AgI$ being yellow in colour. This can be explained by Fajan's rule. Larger the anion more is the polarizability of the anion and thus their electrons gets excited by partial absorption of visible light. Hence, $AgI$ is yellow in colour. So, option (c) is the correct answer.