Why is the first ionisation enthalpy of Cr lo | vedclass

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(A) The electronic configuration of $Cr$ $(Z=24)$ is $[Ar] 3d^5 4s^1$ and $Zn$ $(Z=30)$ is $[Ar] 3d^{10} 4s^2$.In $Cr$,the electron is removed from th

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$Cr$ has a stable $d^5$ configuration.

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(A) The electronic configuration of $Cr$ $(Z=24)$ is $[Ar] 3d^5 4s^1$ and $Zn$ $(Z=30)$ is $[Ar] 3d^{10} 4s^2$.In $Cr$,the electron is removed from the $4s$ orbital,which is relatively easier due to the stability gained by the resulting $3d^5$ half-filled configuration.In $Zn$,the electron is removed from a completely filled $4s^2$ orbital,and the $3d^{10}$ configuration is already very stable,requiring more energy to remove an electron.Therefore,the first ionisation enthalpy of $Cr$ is lower than that of $Zn$.

Why is the first ionisation enthalpy of $Cr$ lower than that of $Zn$?

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