The outer electron configuration of $Gd$ (Atomic No.: $64$) is:

The electronic configuration $3d^{10}4s^0$ is exhibited by which of the following ions?

Elements after atomic number $103$ have been discovered. If an element with atomic number $106$ is considered,which of the following electronic configurations will it possess?

Highest $(+7)$ oxidation state is shown by

The aqueous solution containing which one of the following ions will be colourless?

How do the oxidation states of the elements vary in the transition series?