Statement I : Limestone decomposes when it is heated in air .
Statement II : Increase in the content of `CO_(2)` in the atmosphere in recent years is mainly due to the using of limestone in the manufacture of cement.

Options

A. Both the statements are individually true and Statement II is the correct explanation of Statement I
B. Both the statements are individually true but Statement II is not correct explanation of Statement I
C. Statement I is true and Statement II is false
D. Statement I is false but Statement II is true

Answer

To analyze the statements provided in the question, we need to evaluate each statement separately.

### Step 1: Evaluate Statement I
**Statement I**: Limestone decomposes when it is heated in air.

1. **Identify the chemical composition of limestone**: Limestone is primarily composed of calcium carbonate (CaCO₃).
2. **Understand the decomposition reaction**: When limestone is heated, it undergoes thermal decomposition:
\[ \text{CaCO}_3 (s) \rightarrow \text{CaO} (s) + \text{CO}_2 (g) \]
This reaction shows that calcium carbonate decomposes into calcium oxide (quicklime) and carbon dioxide gas when heated.
3. **Conclusion for Statement I**: Since the reaction is valid and limestone does decompose upon heating, Statement I is **true**.

### Step 2: Evaluate Statement II
**Statement II**: The increase in the content of CO₂ in the atmosphere in recent years is mainly due to the use of limestone in the manufacture of cement.

1. **Understand the role of limestone in cement production**: Limestone is indeed used in the manufacture of cement, and during this process, CO₂ is released as a byproduct.
2. **Consider other sources of CO₂ emissions**: However, the primary contributors to the increase in atmospheric CO₂ levels are:
- Industrial pollution from burning fossil fuels (like coal, oil, and natural gas).
- Emissions from vehicles (vehicular pollution).
- Deforestation and land-use changes.
3. **Conclusion for Statement II**: While limestone usage in cement production contributes to CO₂ emissions, it is not the main reason for the increase in atmospheric CO₂ levels. Therefore, Statement II is **false**.

### Final Conclusion
- Statement I is **true**.
- Statement II is **false**.

Thus, the correct option based on the evaluation of the statements is that Statement I is true and Statement II is false.

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