Among the following chemical reactions the irreversible reaction is

Options

A. `H_(2)+I_(2)rarr2HI`
B. `AgNO_(3)+NaClrarrAgCl+NaNO_(3)`
C. `CaCO_(3)rarr CaO+CO_(2)`
D. `O_(2)+2SO_(2)rarr2SO_(3)`

Answer

To determine which of the given chemical reactions is irreversible, we need to analyze the nature of each reaction. Irreversible reactions typically proceed in one direction and do not easily revert to their original reactants. Here’s a step-by-step solution:

### Step 1: Identify the Reactions
First, we need to list the reactions provided in the question. Since the specific reactions are not given in the question, let's assume we have a few common types of reactions to analyze:
1. **Neutralization Reaction**: Acid + Base → Salt + Water
2. **Decomposition Reaction**: AB → A + B
3. **Synthesis Reaction**: A + B → AB
4. **Precipitation Reaction**: A + B → AB (where AB is a solid precipitate)

### Step 2: Analyze Each Reaction Type
- **Neutralization Reaction**: This is often irreversible because once the acid and base react to form salt and water, they do not easily revert back to their original forms.

- **Decomposition Reaction**: This can be irreversible if the products are gases or if the reaction requires a significant amount of energy to reverse. For example, the decomposition of potassium chlorate (KClO3) into potassium chloride (KCl) and oxygen (O2) is typically irreversible under normal conditions.

- **Synthesis Reaction**: These reactions can be reversible or irreversible depending on the conditions. For example, the formation of water from hydrogen and oxygen can be reversed under certain conditions.

- **Precipitation Reaction**: This is generally irreversible because once a solid precipitate forms, it is difficult to convert it back into the original reactants in a simple manner.

### Step 3: Determine the Irreversible Reaction
Based on the analysis:
- The **neutralization reaction** and **precipitation reaction** are typically irreversible.
- The **decomposition reaction** can also be irreversible depending on the products formed.
- The **synthesis reaction** can be reversible.

### Conclusion
Among the reactions analyzed, the **neutralization reaction** and **precipitation reaction** are good candidates for irreversible reactions. However, if we are to choose one, the **precipitation reaction** is often considered irreversible due to the formation of a solid precipitate that does not easily revert to its original reactants.

### Final Answer
The irreversible reaction among the given options is the **precipitation reaction**.

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