Answer
a) 3+
b) 4
c) Oxalate
Work Step by Step
a) Oxalate has a charge of 2- and since there are two they have total charge of 4-. Since the entire compound has a charge of 1-, chromium has a charge of 3+
b) There are four ligands thus the coordination number is four
c) Oxalate is a bidentate ligand
