To which block does the element with atomic number $106$ belong?

Which of the following types of metals form the most effective catalysts?

Which element from the following is the last element of the $5d$-transition series?

Identify the correct statements from the following: $(i)$ $Ti(IV)$ is more stable than $Ti(III)$ and $Ti(II)$ $(ii)$ Among $3d-$series elements (from $Z=22$ to $29$) only copper has positive reduction potential $(M^{2+} / M)$ $(iii)$ Both $Sc$ and $Zn$ exhibit $+1$ oxidation state

Which one of the following characteristics of the transition metals is associated with their catalytic activity?

Which element from the following exhibits the highest number of various different possible oxidation states?