Transition elements show high melting points. Why?

The element with which of the following outer electron configuration may exhibit the largest number of oxidation states in its compounds?

Explain $d$-block elements of the periodic table.

The pair of ions with paramagnetic nature and same number of electrons is

Find the correct order of the given elements with respect to their size.

Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ An element or its ion that does not have a completely filled $d$-orbital is considered a transition element.
$(b)$ $Sc$ is a transition element.
$(c)$ $Zn$ is a transition element.
$(d)$ The energy difference between $(n-1)d$ and $ns$ orbitals is high.