Q.

Which of the following set of ions act as oxidising agents        [2024]

1 Ce4+ and Tb4+  
2 La3+ and Lu3+  
3 Eu2+ and Yb2+  
4 Eu2+ and Tb4+  

Ans.

(1)

The formation of Ce(IV) is favoured by its noble gas configuration, but it is a strong oxidant reverting to the common +3 state. The E° value for Ce4+/Ce3+ is +1.74 V which suggests that it can oxidise water. Tb(IV) has half-filled f-orbitals and is an oxidant.