The maximum number of unpaired electrons is present in

Which of the following elements exhibits ferromagnetic properties?

In the $3d$ series of $d-$block elements,which of the following elements has the maximum atomic size?

The electronic structure $(n - 1)d^{1 - 10}ns^{0 - 2}$ is characteristic of

The element with an atomic number $26$ is

Assertion : Cuprous ion $(Cu^+)$ has unpaired electrons while cupric ion $(Cu^{2+})$ does not.
Reason : Cuprous ion $(Cu^+)$ is colourless whereas cupric ion $(Cu^{2+})$ is blue in the aqueous solution.