Why do transition elements exhibit variable oxidation states ?

Why do the first row transition elements exhibit variable oxidation states?

(i) What are transition elements ? (ii) Why do transition elements show variable oxidation states ?

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).

Which element exhibits variable oxidation states ?

Why do transition elements show variable oxidation states? Write the name of a 3d-series element that exhibits maximum oxidation states.