Q. For $d$-block elements the first ionisation potential is of the order
A) $Zn\ > Fe > \ Cu > Cr$
B) $Sc\ = Ti\ < V\ = Cr$
C) $Zn < Cu < Ni < Co$
D) $V > \ Cr > Mn > Fe$
Explanation
(a)
The ionisation energies increase with increasing atomic number. The trend is irregular among $d$-block elements.
[table] Element | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn ; IE ($\mathbf{kJ/mo}\mathbf{l}^{\mathbf{- 1}}\mathbf{)}$ | 631 | 656 | 650 | 652 | 717 | 762 | 758 | 736 | 745 | 905 [/table]
$\therefore\ \ \ Zn > Fe > Cu > Cr$ is correct order.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.