Which of the following easily catalyse the decomposition of `H_(2)O_(2)` when stored ?
(i) Rough surface
(ii) Sunlight
(iii) Dust particles
(iv) Metals

Options

A. (i) and (ii)
B. (i),(ii) and (iii)
C. (ii) and (iv)
D. All of these.

Explanation

To determine which of the given options easily catalyze the decomposition of hydrogen peroxide (H₂O₂) when stored, we need to analyze each option based on the properties of H₂O₂ and its decomposition process.

### Step-by-Step Solution:

1. **Understanding Hydrogen Peroxide (H₂O₂)**:
- H₂O₂ is a strong oxidizing agent and can decompose into water (H₂O) and oxygen (O₂). The decomposition can be represented as:
\[ 2 \text{H}_2\text{O}_2 \rightarrow 2 \text{H}_2\text{O} + \text{O}_2 \]
- The bond between the two oxygen atoms in H₂O₂ is weak, which makes it prone to decomposition.

2. **Identifying Catalysts**:
- Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. In the case of H₂O₂, certain conditions and substances can act as catalysts.

3. **Analyzing Each Option**:
- **(i) Rough surface**: A rough surface can provide more area for reaction but is not a typical catalyst for H₂O₂ decomposition.
- **(ii) Sunlight**: Sunlight, particularly UV light, can significantly accelerate the decomposition of H₂O₂. It is known that H₂O₂ should be stored in dark places to prevent rapid decomposition due to sunlight.
- **(iii) Dust particles**: Dust can contain various substances, but it is not a reliable catalyst for H₂O₂ decomposition.
- **(iv) Metals**: Certain metals and their oxides (like iron oxide, manganese compounds) are known to catalyze the decomposition of H₂O₂ effectively.

4. **Conclusion**:
- The options that easily catalyze the decomposition of H₂O₂ when stored are **(ii) Sunlight** and **(iv) Metals**. Therefore, the correct answer is:
- **(ii) Sunlight and (iv) Metals**.

### Final Answer:
The correct options are **(ii) Sunlight and (iv) Metals**.