In the periodic table,the first transition series is placed in:

Which of the following has the maximum number of unpaired electrons?

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.

Which of the following metals make the most efficient catalyst?

In which block does the $106^{th}$ element belong?

Identify the pair in which both elements typically exhibit only one oxidation state.