Which of the following reaction is not involved in thermite process?

Options

A. `3Mn_(3)O_(4) + 8 Al rarr 9 Mn + 4Al_(2)O_(3)`
B. `Cr_(2)O_(3) + 2 Al rarr Al_(2)O_(3) + 2Cr`
C. `2Fe + Al_(2)O_(3) rarr 2Al + Fe_(2)O_(3)`
D. `B_(2)O_(3) + 2Al rarr 2B + Al_(2)O_(3)`

Answer

To determine which reaction is not involved in the thermite process, we need to understand what the thermite process entails. The thermite process, also known as the aluminum thermite process, is a type of exothermic reaction where aluminum acts as a reducing agent to reduce metal oxides to their respective metals.

### Step-by-Step Solution:

1. **Understand the Thermite Process**:
- The thermite process involves a reaction between aluminum powder and a metal oxide. The aluminum reduces the metal oxide to produce the metal and aluminum oxide (Al2O3) as a byproduct.

2. **Analyze Each Reaction**:
- **Option 1**: \(3Mn_3O_4 + 8Al \rightarrow 9Mn + 4Al_2O_3\)
- This reaction involves aluminum reducing manganese(IV) oxide to manganese. This is a thermite reaction.

- **Option 2**: \(Cr_2O_3 + 2Al \rightarrow Al_2O_3 + 2Cr\)
- Here, aluminum reduces chromium(III) oxide to chromium. This is also a thermite reaction.

- **Option 3**: \(2Fe + Al_2O_3 \rightarrow 2Al + Fe_2O_3\)
- In this reaction, aluminum oxide is being used as a reactant to produce aluminum and iron(III) oxide. This is not a thermite reaction because it does not involve aluminum reducing a metal oxide; instead, it involves the oxidation of aluminum.

- **Option 4**: \(B_2O_3 + 2Al \rightarrow 2B + Al_2O_3\)
- This reaction shows aluminum reducing boron oxide to boron, which is a thermite reaction.

3. **Conclusion**:
- The reaction that is not involved in the thermite process is **Option 3**: \(2Fe + Al_2O_3 \rightarrow 2Al + Fe_2O_3\).

### Final Answer:
The reaction that is not involved in the thermite process is **Option 3**: \(2Fe + Al_2O_3 \rightarrow 2Al + Fe_2O_3\).