Which of the following reactions are kinetically favourable ?
I. `[Cu(H_(2)O)_(4)]^(2+)+4NH_(3)rarr[Cu(NH_(3))_(4)]^(2+)+4H_(2)O`
II. `[Cu(H_(2)O)_(4)]^(2+)+4Cl^(-)rarr[CuCl_(4)]^(2-)+4H_(2)O`
III. `[Co(H_(2)O)_(6)]^(3+)+6Cl^(-)rarr[CoCl_(6)]^(3-)+6H_(2)O`

Options

A. I and II
B. II and III
C. I and III
D. I, II and III

Explanation

To determine which of the given reactions are kinetically favorable, we need to analyze the stability of the complexes involved and the nature of the ligands.

### Step 1: Analyze Reaction I
**Reaction I:**
\[ [Cu(H_2O)_4]^{2+} + 4NH_3 \rightarrow [Cu(NH_3)_4]^{2+} + 4H_2O \]

- In this reaction, copper is in the +2 oxidation state in both the reactant and product.
- Ammonia (NH₃) is a stronger field ligand compared to water (H₂O), which means it can stabilize the copper complex more effectively.
- The transition from water to ammonia ligands is favorable because it leads to a more stable complex. Thus, this reaction is kinetically favorable.

### Step 2: Analyze Reaction II
**Reaction II:**
\[ [Cu(H_2O)_4]^{2+} + 4Cl^{-} \rightarrow [CuCl_4]^{2-} + 4H_2O \]

- Here, copper is again in the +2 oxidation state.
- Chloride (Cl⁻) is a weaker field ligand compared to water and ammonia. The formation of the tetrahedral complex \([CuCl_4]^{2-}\) is less stable than the octahedral complex \([Cu(H_2O)_4]^{2+}\).
- Therefore, this reaction is not kinetically favorable because the product is less stable than the reactant.

### Step 3: Analyze Reaction III
**Reaction III:**
\[ [Co(H_2O)_6]^{3+} + 6Cl^{-} \rightarrow [CoCl_6]^{3-} + 6H_2O \]

- In this case, cobalt is in the +3 oxidation state in both the reactant and product.
- The complex \([Co(H_2O)_6]^{3+}\) is relatively stable, and the formation of \([CoCl_6]^{3-}\) involves a change in coordination number and geometry.
- However, cobalt in the +3 state is more stable with strong field ligands, and chloride is a weaker field ligand. Thus, this reaction is not kinetically favorable because the reactant is more stable than the product.

### Conclusion
Based on the analysis:
- **Kinetically favorable reactions:** I
- **Not kinetically favorable reactions:** II and III

### Summary of Results
- **Reaction I:** Kinetically favorable
- **Reaction II:** Not favorable
- **Reaction III:** Not favorable