Why `PbX_2` is more stable than `PbX_4`?.

Explanation

`PbCl_(2)` is an inic cyrstalline solid while `PbCl_(4)` is a molecular solid in which `PbCl_(4)` molecules are covalent in nature. This is becaue of smaller size and more positive charge on `Pb^(4+)` ion as compared to `Pb^(2+)` ion. The former polarises the anions more than the latter and the compound acquires covalent nature. thus, `PbCl_(4)` has less melting point htan `pbCl_(2)`, and therefore, it is less stable.