Correct Option
The correct option is (a).
Explanation
Coal is a fossil fuel formed through the geological process of carbonization. This involves the slow conversion of dead vegetation into carbon-rich sedimentary rock under specific environmental conditions over millions of years.
Statement-wise Analysis:
- Statement 1 is Correct: Coal formation began approximately 300 million years ago (during the Carboniferous period). The earth had dense forests in low-lying wetland areas. Due to natural processes like flooding, these forests were buried under the soil.
- Statement 2 is Incorrect: The process did not involve complete decomposition into compost. Compost forms through aerobic decomposition (in the presence of oxygen). Coal formation requires anaerobic conditions (absence of air) which prevents complete decay, initially turning the vegetation into peat rather than compost.
- Statement 3 is Incorrect: As more soil deposited over the buried vegetation, the layers were compressed. As the vegetation sank deeper, the temperature rose and the pressure increased. The conversion of dead vegetation into coal requires high pressure and high temperature inside the earth, not low conditions.
Key Takeaway:
Coal is formed by the carbonization of buried vegetation under conditions of high temperature and high pressure, which progressively transforms peat into lignite, bituminous coal, and finally anthracite.