Give the oxidation state, d-orbitals occupation and coordination number of the central metal ion in the following complexes:
(i). `K_3[Co(C_2O_4)_3]`
(ii). `cis-[Cr(en)_2Cl_2]Cl`
(iii). `(NH_4)_2[CoF_4]`
(iv). `[Mn(H_2O)]SO_4`

Explanation

To solve the question regarding the oxidation state, d-orbital occupation, and coordination number of the central metal ion in the given complexes, we will analyze each complex step by step.

### (i) For `K3[Co(C2O4)3]`:

1. **Identify the central metal ion**: The central metal ion is cobalt (Co).
2. **Determine the oxidation state of cobalt**:
- Let the oxidation state of Co be \( x \).
- The oxalate ion \( C_2O_4^{2-} \) has an oxidation state of -2. Since there are 3 oxalate ions, the total contribution is \( 3 \times (-2) = -6 \).
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