• # question_answer Which compound from each of the following pairs is more covalent and why? (a) CuO or CuS (b) $AgCl$ or $AgI$ (c) $PbC{{l}_{2}}$ or $PbC{{l}_{4}}$ (d) $BeC{{l}_{2}}$ or $MgC{{l}_{2}}$

This is explained with the help of Fazan's rules (a) CuS is more covalent than CuO because ${{S}^{2-}}$ ion is more polarised than the ${{O}^{2-}}$ ion due to bigger size. (b) $AgI$ is more covalent than$AgCl$  because${{I}^{-}}$ ion is more polarised than$C{{l}^{-}}$ ion due to bigger size. (c)$PbC{{l}_{4}}$ is more covalent than $PbC{{l}_{2}}$ because $P{{b}^{4+}}$ ion due to smaller size and greater magnitude of positive charge is more polarising than $P{{b}^{2+}}$ion. (d)$BeC{{l}_{2}}$ is more covalent than $MgC{{l}_{2}}$ because the $B{{e}^{2+}}$ ion is more polarising than$M{{g}^{2+}}$ ion due to smaller size.