In the manufacture of `H_(2)SO_(4)` by contact process, the presence of `As_(2)O_(3)` acts as :-

Options

A. Catalytic promoter
B. Catalytic poison
C. Induced catalyst
D. Autocatalyst

Answer

To solve the question regarding the role of `As_(2)O_(3)` in the manufacture of `H_(2)SO_(4)` by the contact process, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Contact Process**: The contact process is a method used to produce sulfuric acid (`H_(2)SO_(4)`) from sulfur dioxide (`SO_(2)`) and oxygen (`O_(2)`) in the presence of a catalyst, typically vanadium pentoxide (`V_(2)O_(5)`).

2. **Identify the Role of `As_(2)O_(3)`**: In this process, `As_(2)O_(3)` (arsenic trioxide) is mentioned. We need to determine whether it acts as a catalytic promoter, catalytic poison, induced catalyst, or autocatalyst.

3. **Define Catalytic Poison**: A catalytic poison is a substance that decreases the activity of a catalyst. It can bind to the active sites of the catalyst, thereby inhibiting the reaction it is supposed to facilitate.

4. **Analyze the Effect of `As_(2)O_(3)`**: It is known that `As_(2)O_(3)` can inhibit the activity of catalysts used in the contact process. This means that it reduces the efficiency of the catalyst in promoting the reaction.

5. **Conclusion**: Since `As_(2)O_(3)` decreases the activity of the catalyst in the contact process, it acts as a catalytic poison. Therefore, the correct answer to the question is that `As_(2)O_(3)` acts as a catalytic poison.

### Final Answer:
`As_(2)O_(3)` acts as a **catalytic poison** in the manufacture of `H_(2)SO_(4)` by the contact process.

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