Which of the following ions are diamagnetic?

To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.

Determine the name and symbol of the element with atomic number $103$.

Gadolinium (atomic number $= 64$) is a member of the $4f$ series. Its electronic configuration in the $+3$ oxidation state is $[Xe] 4f^7$. What is the ground state electronic configuration of gadolinium?

The element having the electronic configuration $[Kr] 4d^{10} 4f^{14} 5s^2 5p^6 5d^2 6s^2$ belongs to:

Which of the following pairs exhibit color in aqueous medium?