These metals exhibit autocomplexation:

• A. Noble metals
• B. Volatile metals
• C. Coinage metals
• D. Alkaline earth metals

Answer: (B)

Autocomplexation happens when a metal can form a complex using ligands that are derived from the same metal species, allowing self-assembly into dimers or higher assemblies. Metals that are volatile can readily form and sustain volatile metal halide or similar complexes in solution or the gas phase. Those volatile metal complexes can bridge between metal centers, letting a metal ion coordinate to another metal center via shared ligands formed from the metal itself. This tendency to form and exchange such self-derived ligands makes autocomplexes more accessible for volatile metals.

Other groups—noble metals, coinage metals, and alkaline earth metals—don’t as readily form these self-assembled, volatile self-ligand complexes under typical conditions, so autocomplexation is less characteristic for them.