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

As size of the anion increases the polarisation increases and hence the color intensity of the compound increases.

The larger the anionic radius, the greater is its tendency to get polarised. The higher polarisability of $I^{-}$ ion, owing to its larger radius, facilitates the transition of electron (from anion to metal ion) in the visible range, imparting yellow colour to AgI. on the other hand, lower polarisability of $C{l}^{-}$ ion, facilitates the transition of an electron in the UV range. hence, AgCl appears white.

Hence, $AgI$ is yellow in colour. So, option (c) is the correct answer.