Why do transition metals form complexes ?

Explain the following: Why do transition metals form alloys readily?

Why do transition metals and their compounds are found to be good catalysts and form alloys ?

Transition elements form complexes easily ? Justify.

Why most of the compounds of transition metal are coloured ?

Why transition elements form a number of alloys ?

Why transition elements form a large number of alloys ?

Why do transition elements show variable oxidation states ? Name the element showing maximum number of oxidation states among the first series of transition metals from Sc (Z = 21) to Zn (Z= 30).