Question

The stability of ferric ion is due to:

• A. half filled $f-$ orbitals
• B. half filled $d-$ orbitals
• C. completely filled $f-$ orbitals
• D. completely filled $d-$ orbitals

Answer 1

Answer: (B)

half filled $d-$ orbitals

Answer 2

$Fe ^{3+}$ ion has the following configuration
$Fe ^{3+}=1 s^{2}, 2 s^{2} 2 p^{6}, 3 s^{2} 3 p^{6} 3 d^{5}$
Hence, ferric ion is quite stable due to half-filled d-orbitals.