Which of the following is not an example of disproportionation reaction ?

Options

A. `4ClO_(3)^(-)rarr Cl^(-)+3ClO_(4)^(-)`
B. `2H_(2)O_(2)rarr 2H_(2)O + O_(2)`
C. `2NO_(2)+2OH^(-)rarr NO_(3)^(-)+H_(2)O`
D. `TiCl_(4)+2Mg rarr Ti + 2MgCl_(2)`

Explanation

To determine which of the following is not an example of a disproportionation reaction, we first need to understand what a disproportionation reaction is. A disproportionation reaction is a type of redox reaction in which a single substance is both oxidized and reduced, resulting in the formation of two different products.

### Step-by-Step Solution:

1. **Identify the Concept of Disproportionation**:
- A disproportionation reaction involves a reactant that undergoes both oxidation and reduction simultaneously.

2. **Analyze Each Given Option**:
- For each option provided in the question (not specified here), we will need to determine if the reactant is being oxidized and reduced.

3. **Example Analysis**:
- **Chlorine Compounds**:
- Consider a reaction where Cl changes from +7 to +5 (reduction) and from +7 to -1 (oxidation). This is a disproportionation reaction.
- **Hydrogen Peroxide (H2O2)**:
- In H2O2, the oxidation state of O changes from -1 to -2 (oxidation) and from -1 to 0 (reduction). This is also a disproportionation reaction.
- **Nitrogen Dioxide (NO2)**:
- Analyze the oxidation states of nitrogen in NO2. If it changes from +4 to +3 (reduction) and +4 to +5 (oxidation), it is a disproportionation reaction.
- **Thallium Compounds (TlCl4)**:
- Check the oxidation states in TlCl4. If thallium changes from +1 to +2 and +1 to -1, this indicates a disproportionation reaction.
- **Thallium Chloride (TlCl4)**:
- If the oxidation states do not show both oxidation and reduction for the same element, it is not a disproportionation reaction.

4. **Conclusion**:
- After analyzing all options, we find that the one that does not show simultaneous oxidation and reduction of the same element is the answer. Based on the analysis, TlCl4 does not exhibit disproportionation.

### Final Answer:
- The option that is **not** an example of a disproportionation reaction is **TlCl4**.