Question

According to Fajans rule covalent bond is favoured by:

• A. small cation and large anion
• B. small cation and small anion
• C. large cation and large anion
• D. large cation and small anion

Answer 1

Answer: (A)

According to Fajans rule : (i) The cations with smaller size have higher polarising power. (ii)The anions with large size have high polarisability. (iii)There should be high charge on cation or theanionorboth. (iv) Cations with pseudo inert gas configuration $(n{s}^2{p}^6{d}^{10})$ or with inert pair configuration $d^{10}(n+1)s^2,$ have high polarising power, while cations with noble gas configuration $(n{s}^2{p}^6)$ have low polarising power.