The 4d and 5d series of transition metals have more frequency metal-metal bonding in their compounds than do the 3d metals. Explain.

Explanation

In the same group of d-block elements, the 4d and 5d transition elements has larger size than that of 3d element. Thus, the valence electrons are less tightly held and hence can form metal-metal bond more frequently. (That is why melting points of 4d and 5d series as well as enthalpies of atomisation are higher than those of 3d series).