Question

How many of the following statement(s) is/are correct
1.First ionisation energy of Zn is higher than Cu
2.First ionisation energy of Cu is higher than Zn
3.Second ionisation energy of Zn is lesser than Cu
4.Both Zn and Cu has similar first ionisation energy

Answer 1

$\text{Electronic configuration of Zn}:\left[Ar\right]3d^{10}4s^2$
$\text{Electronic configuration of Cu}:\left[Ar\right]3d^{10}4s^1$

In Zn, the orbitals are fully filled and are stable so abstraction of electron from its orbital is difficult so they have higher first ionisation energy than Cu.

Second ionisation energy for Cu is more because it removes electrons from fully filled d-orbital of Cu whereas second ionisation in Zn leads again to stable fully filled d-orbital.

Hence, statements (1) and (3) are correct.