Which of the following reaction is not of the first order ?

Options

A. Inverison of sucrose in the presence of acid
B. Acid-catalyzed hydrolyiss of ethyl acetate
C. Hydrolyiss of tertiary butyl halide uisng alkali
D. Oxidation of `I^(ɵ)` ion by `S_(2)O_(8)^(2-)` ion

Explanation

To determine which of the following reactions is not of the first order, we need to analyze each reaction based on the definition of first-order reactions. A first-order reaction is characterized by a rate that depends linearly on the concentration of one reactant.

### Step-by-Step Solution:

1. **Understand First-Order Reactions**:
- First-order reactions have a rate equation of the form:
\[ \text{Rate} = k[A]^1 \]
- Here, \( k \) is the rate constant and \([A]\) is the concentration of the reactant.

2. **Analyze Each Reaction**:
- **Reaction 1**: Inversion of sucrose in the presence of acid.
- This is a well-known first-order reaction because the rate depends on the concentration of sucrose.
- **Reaction 2**: Acid-catalyzed hydrolysis of ethyl acetate.
- This reaction is also first-order with respect to ethyl acetate as the rate depends on its concentration.
- **Reaction 3**: Hydrolysis of tertiary butyl halide using alkali.
- This reaction is first-order because the rate depends on the concentration of the tertiary butyl halide.
- **Reaction 4**: Oxidation of iodide ion by \( S_2O_8^{2-} \).
- This reaction is second-order because the rate depends on the concentrations of both iodide ions and \( S_2O_8^{2-} \).

3. **Identify the Non-First Order Reaction**:
- Among the reactions analyzed, the oxidation of iodide ion by \( S_2O_8^{2-} \) is the only reaction that is not first-order. It is a second-order reaction.

4. **Conclusion**:
- The reaction that is not of the first order is the oxidation of iodide ion by \( S_2O_8^{2-} \).

### Final Answer:
The reaction that is not of the first order is the oxidation of iodide ion by \( S_2O_8^{2-} \) (Option 3).

---