Lignite, bituminous, and anthracite are different ranks of which substance?

Coal is a fossil fuel formed from plant material that has been subjected to heat and pressure over millions of years. It exists in different ranks based on carbon content, energy density, and hardness, which reflect the degree of metamorphism the material has undergone. The main ranks of coal are lignite, bituminous, and anthracite.

1. 
   

   Lignite, also called brown coal, is the lowest rank of coal. It has a low carbon content (around 25–35%) and high moisture, making it softer and less energy-dense. Lignite is mainly used in electricity generation near coal mines.

   
   


2. 
   

   Bituminous coal is a medium-rank coal with higher carbon content (45–86%) and greater energy value. It is harder and used for power generation, steel production, and industrial fuel.

   
   


3. 
   

   Anthracite is the highest rank of coal, containing 86–97% carbon. It is hard, glossy, and produces very high heat with minimal smoke. Anthracite is used in specialized industrial processes and residential heating.

   
   

Coal formation occurs in stages: plant material → peat → lignite → bituminous coal → anthracite. The carbon content increases, moisture decreases, and energy content rises with each stage. This classification helps in choosing coal for specific industrial or domestic applications.

The other options are incorrect:

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  Iron is a metal, not a fossil fuel.

  
  


• 
  

  Wood is organic but not a type of coal.

  
  

In summary, lignite, bituminous, and anthracite are different ranks of coal, reflecting their carbon content, hardness, and energy value. This knowledge is important for understanding fossil fuels, energy resources, and their practical applications in chemistry, industry, and everyday science.