Question

the complex that will not exhibit paramagnetic behaviour is [atomic number:Fe = 26 Cu =29]​

Answer 1

Answer:

the element copper which is present in the in the d - block elements do not show paramagnetic behavior

Explanation:

Answer 2

Paramagnetic compounds contain one or more unpaired electrons and are attracted to the poles of a magnet.

Fe=26

The Fe2+ ion has 3d6 as the electron configuration. Because it has 4 unpaired electrons, it is paramagnetic. Fe³⁺ has one electron unpaired. Hence it is paramagnetic. Elemental Fe and Fe3+ are paramagnetic because of the necessity of unpaired electrons in their orbitals.

Cu=29

The element copper which is present in the d - block elements does not show paramagnetic behavior because the electronic configuration of Copper (Cu) is $3d^{10} 4s^1$. In Copper ($Cu^+$) the electronic configuration is $3d^{10}$ which is completely filled d-shell thus it is diamagnetic. In the case of $Cu^{2+}$ the electronic configuration is $3d^9$ thus, it has one unpaired electron in d-subshell thus it is paramagnetic.

So, Copper(Cu=29) will not exhibit paramagnetic behaviour.