Which of the following transition metal oxides is most readily reduced to the corresponding free metal by heating with dihydrogen?

Step-by-step solution

The ease of reduction of a metal oxide to the free metal depends on the thermodynamic stability of the oxide and the standard reduction potential of the metal. Metals from the early 3d series (such as Ti, Cr, and Mn) are highly electropositive, and their oxides are very stable. They require strong reducing agents (like carbon or aluminium) at high temperatures for reduction. Copper, however, has a positive standard reduction potential ( E^ _ Cu ²⁺/ Cu = +0.34 V ), making its oxide ( CuO ) relatively less stable. Th