The correct option is Anthracite.
Explanation
Coal is classified into different grades based on the degree of compression, depth of burial, and time taken during formation. The quality of coal is primarily determined by its carbon content, moisture, and calorific value. The four major types of coal are Peat, Lignite, Bituminous, and Anthracite.
Option Analysis
- Anthracite: This is the highest quality hard coal. It is characterized by a carbon content of 80% to 95%. It is hard, compact, jet black, and burns slowly with a blue flame without smoke. It has the highest heating value. In India, it is found only in Jammu and Kashmir.
- Bituminous: This is the most popular coal in commercial use. It has a carbon content of 60% to 80%. It is dense, black, and brittle. High-grade bituminous coal is used in blast furnaces for smelting iron.
- Lignite: Also known as brown coal, it is a low-grade coal. It contains about 40% to 55% carbon. It is soft with high moisture content and low heating value.
- Peat: This represents the first stage of transformation from wood to coal. It has a low carbon content (less than 40%), high moisture, and low heating capacity.
Key Takeaway
Anthracite is the superior form of coal due to its high carbon density (80-95%) and low impurity levels, making it the most efficient fuel source among coal varieties.