The coordination numbers of `Co` and `Al` in `[Co(Cl(en)_(2)]Cl` and `K_(3)[Al(C_(2)O_(4))_(3)]`, respectively are :
(en= ethane-1,-1-diamine).

Options

A. 5 and 3
B. 3 and 3
C. 6 and 6
D. 5 and 6

Answer

To find the coordination numbers of cobalt (Co) and aluminum (Al) in the complexes \([Co(Cl)(en)_2]Cl\) and \(K_3[Al(C_2O_4)_3]\), we will analyze each complex step by step.

### Step 1: Analyze the first complex \([Co(Cl)(en)_2]Cl\)

1. **Identify the ligands**: The ligands in this complex are:
- Chloride ion (Cl)
- Ethylene diamine (en), which is a bidentate ligand.

2. **Determine the contribution of each ligand to the coordination number**:
- The chloride ion (Cl) can donate one pair of electrons, contributing **1** to the coordination number.
- Ethylene diamine (en) is a bidentate ligand, meaning it can attach through two donor atoms (the nitrogen atoms). Since there are two ethylene diamine ligands, they contribute **2 × 2 = 4** to the coordination number.

3. **Calculate the total coordination number**:
- Total coordination number = Contribution from Cl + Contribution from en
- Total coordination number = \(1 + 4 = 5\)

### Step 2: Analyze the second complex \(K_3[Al(C_2O_4)_3]\)

1. **Identify the ligands**: The ligand in this complex is:
- Oxalate ion (\(C_2O_4^{2-}\)), which is also a bidentate ligand.

2. **Determine the contribution of the oxalate ligands**:
- Each oxalate ion can donate two pairs of electrons, contributing **2** to the coordination number.
- Since there are three oxalate ligands, they contribute **3 × 2 = 6** to the coordination number.

3. **Calculate the total coordination number**:
- Total coordination number = Contribution from oxalate ligands
- Total coordination number = \(6\)

### Final Answer:
- The coordination number of cobalt (Co) in \([Co(Cl)(en)_2]Cl\) is **5**.
- The coordination number of aluminum (Al) in \(K_3[Al(C_2O_4)_3]\) is **6**.

### Summary:
- Coordination number of Co: **5**
- Coordination number of Al: **6**