3. Coal classification is critical for its utilization in different industries. Describe the classification of coal based on its rank. Compare and contrast the physical and chemical properties of lignite, sub-bituminous, bituminous, and anthracite coal, and discuss their respective uses in industry.
4. Detail the environmental impacts of coal mining and combustion. Discuss the major pollutants released, their effects on air and water quality, and the health implications for humans and ecosystems. Additionally, describe the technologies and strategies employed to mitigate these environmental impacts.