Four successive members of the first two transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy?

Step-by-step solution

V ²⁺(21)[ Ar ]¹⁸ 3 d^3 4 s^0 Cr ²⁺ (22) [ Ar ]¹⁸ 3 d^4 4 s^0 Mn ²⁺ (23) [ Ar ]¹⁸ 3 d^5 4 s^0 Fe ²⁺(24) [ Ar ]¹⁸ 3 d^5 4 s^1 The value of the third ionization enthalpy will be the largest in the case of manganese as the electrons in the orbitals are in half-filled stable electronic configuration and a very large amount of energy is required to overcome this effect.