Question

Which among the following element has the highest third ionisation enthalpy?

• A. Vanadium
• B. Chromium
• C. Manganese
• D. Iron

Answer 1

Answer: (C)

V²⁺ (21) [ Ar ]¹⁸ 3d³ 4s⁰
Cr²⁺ (22) [ Ar ]¹⁸ 3d⁴ 4s⁰
Mn²⁺ (23) [ Ar ]¹⁸ 3d⁵ 4s⁰
Fe²⁺ (24) [ Ar ]¹⁸ 3d⁵ 4s¹
To find ionization enthalpy we first see electronic configuration.
Then we see shell.
If shell are same then see charge.
Then see extra stability ( Half filled and fully filled ).
$\Rightarrow I_3(Mn)>I\cdot E_3(Fe)>I_3(Cr)>I_3{E}_3(V)$