COMEDK2025Chemistryd and f Block ElementsActual
Choose the correct ascending order of the second ionisation enthalpies of the given metals. A. Fe ( Z =26) B. Mn (Z=25) C. V(Z=23) D. Cr (Z=24)
Options
- AC < B < A < D
- BA < D < B < C
- CC < A < D < B
- DB < A < D < C
Correct answer
A. C < B < A < D
Step-by-step solution
The second ionisation enthalpy involves the removal of an electron from the M⁺ ion. The electronic configurations of the M⁺ ions are as follows: V ( Z=23 ): [Ar] 3d^3 4s^1 . Removing one electron gives V⁺ : [Ar] 3d^3 4s^1 . The second ionisation involves removing the 4s^1 electron. Cr ( Z=24 ): [Ar] 3d^5 4s^1 . Removing one electron gives Cr⁺ : [Ar] 3d^5 . The second ionisation involves removing an electron from the stable half-filled 3d^5 subshell, which requires high energy. Mn ( Z=25 ): [Ar] 3d^5 4s^2 . Removing