Which is a neutral and symmetrical bidentate ligand?

dipyridyl

The answer is (4) dipyridyl.

Dipyridyl is a bidentate ligand that is symmetrical and neutral. It is a molecule that contains two pyridine rings that can each donate a pair of electrons to a metal atom. The two pyridine rings are identical, and the dipyryl molecule does not have a charge.

The other ligands in the answer choices are not neutral or symmetrical. Oxalate is a bidentate ligand that is symmetrical, but it is not neutral. Gly is a bidentate ligand that is not symmetrical. Dien is a tridentate ligand that is neutral.