Faizan's rule batao koi

Solution:
Fajan's rule helps to predict covalent character in ionic compounds.
The extent to which a cation can polarise an anion depends on the charge density of the cation.
Charge density is defined as the ratio of charge to volume.
Polarising power is directly proportional to charge density.
More the charge density, the greater the polarising power for that cation.
Postulates:
1) Smaller the size of the cation, the larger the size of the anion, and the greater the covalent character of the ionic bond.
2) Greater the charge of cation, the greater the covalent character of the ionic bond.
3) Cations with pseudo noble gas configuration have more covalent character than metal ions having noble gas configuration.