The coordination number and magnetic moment of the complex [Cr(C2O4)2(NH3)2]- can be determined by analyzing the structure and properties of the complex.

Coordination Number:
The coordination number refers to the number of ligands attached directly to the central metal ion in a complex. In the given complex [Cr(C2O4)2(NH3)2]-, we have to identify the ligands that bind to the central chromium (Cr) ion.

- The ligands attached to the central chromium ion are C2O4 (oxalate) and NH3 (ammonia).
- The formula [Cr(C2O4)2(NH3)2]- indicates that there are two C2O4 ligands and two NH3 ligands.
- Each C2O4 ligand has two oxygen atoms that can coordinate with the central chromium ion, and each NH3 ligand has one nitrogen atom.
- Therefore, the total number of ligands directly attached to the central chromium ion is four.

Hence, the coordination number of the complex [Cr(C2O4)2(NH3)2]- is 4.

Magnetic Moment:
The magnetic moment of a complex is related to the number of unpaired electrons present in the complex. To determine the magnetic moment of [Cr(C2O4)2(NH3)2]-, we need to consider the electronic configuration of the central chromium ion.

- Chromium (Cr) has an atomic number of 24, and its electronic configuration is [Ar] 3d5 4s1.
- In the given complex, the oxidation state of chromium is not specified, so we assume it to be +3 for the sake of calculation.
- When Cr3+ forms a complex, it loses three electrons from its 3d orbital, resulting in a configuration of [Ar] 3d3.
- In the 3d3 configuration, there are three unpaired electrons present.
- Each unpaired electron contributes one Bohr magneton (μB) to the magnetic moment.
- Therefore, the magnetic moment of the complex [Cr(C2O4)2(NH3)2]- is 3 μB.

In summary, the coordination number of the complex [Cr(C2O4)2(NH3)2]- is 4, and its magnetic moment is 3 μB, based on the number of ligands directly attached to the central chromium ion and the electronic configuration of the chromium ion, respectively.

Coordination no. 6 and magnetic moment is 3.46BM