Decomposition of `H_(2)O_(2)` can be slowed down by addittion of smass amount phosphoric acid which act as

Options

A. Stopper
B. Inhibitor
C. Detainer
D. Promotor

Answer

To solve the question regarding the effect of phosphoric acid on the decomposition of hydrogen peroxide (H₂O₂), we can follow these steps:

### Step 1: Understand the Reaction
The decomposition of hydrogen peroxide can be represented by the following chemical equation:
\[ 2 H_2O_2 \rightarrow 2 H_2O + O_2 \]
This reaction produces water (H₂O) and oxygen gas (O₂).

**Hint:** Identify the products of the reaction to understand what happens during the decomposition of hydrogen peroxide.

### Step 2: Identify the Role of Phosphoric Acid
Phosphoric acid (H₃PO₄) is added to the reaction. We need to determine how it affects the rate of decomposition of hydrogen peroxide.

**Hint:** Consider the definitions of different types of substances that can affect reaction rates: catalysts, inhibitors, and promoters.

### Step 3: Define Catalyst, Inhibitor, and Promoter
- **Catalyst:** A substance that increases the rate of a reaction.
- **Inhibitor:** A substance that decreases the rate of a reaction.
- **Promoter:** A substance that enhances the effect of a catalyst, thereby increasing the rate of reaction.

**Hint:** Recall that an inhibitor slows down the reaction, while a promoter speeds it up.

### Step 4: Analyze the Effect of Phosphoric Acid
In this case, the addition of phosphoric acid slows down the decomposition of hydrogen peroxide. Therefore, it acts as an inhibitor.

**Hint:** Think about how the addition of a substance can either speed up or slow down a reaction.

### Step 5: Evaluate the Options
Now, we can evaluate the provided options:
1. Stopper - Incorrect, as it does not just stop the reaction.
2. Inhibitor - Correct, as it slows down the reaction.
3. Retainer - Incorrect, as this term does not apply to the context of reaction rates.
4. Promoter - Incorrect, as it would increase the reaction rate.

**Hint:** Cross-check each option with the definitions and the role of phosphoric acid in the reaction.

### Conclusion
The correct answer is that phosphoric acid acts as an **inhibitor** in the decomposition of hydrogen peroxide.

**Final Answer:** Phosphoric acid acts as an inhibitor.