The 4d and 5d-series of transition metals have more frequent 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 metals have larger size than that of 3d-metals. So the valence electrons of 4d and 5d metal atoms are less trightly held and hence these electrons can be involved in the formation of metal-metal bond more easily.