ANS:B - heated charcoal

Heated charcoal, also known as activated carbon or activated charcoal, is a highly porous form of carbon that has been processed to increase its surface area and adsorption capacity. Here's an explanation of heated charcoal:

1. Production: Charcoal is typically produced by heating organic materials, such as wood, coconut shells, or coal, in the absence of oxygen through a process called pyrolysis. This process drives off volatile compounds and leaves behind a carbon-rich material. Activated charcoal is then produced by further heating the charcoal to very high temperatures in the presence of a gas, such as steam or carbon dioxide, which creates pores and increases its surface area.
2. High Surface Area: The heating and activation process create a network of pores and a high surface area per unit volume. The surface area of activated charcoal can range from hundreds to thousands of square meters per gram, providing a large surface for adsorption.
3. Adsorption Properties: The porous structure of activated charcoal allows it to adsorb a wide range of substances onto its surface. It works through a process called adsorption, where molecules of gases, liquids, or dissolved substances adhere to the surface of the charcoal. This makes activated charcoal useful in various applications, including water purification, air filtration, and medical treatments.
4. Applications: Heated charcoal is widely used in various industries and applications:
   • Water Treatment: Activated charcoal is used to remove impurities, odors, and contaminants from water. It can adsorb organic compounds, chlorine, heavy metals, and other pollutants.
   • Air Purification: Activated charcoal filters are used in air purifiers and respirators to remove volatile organic compounds (VOCs), odors, and airborne contaminants.
   • Medical Uses: Activated charcoal is used in medicine to treat poisoning and overdose cases. It can adsorb toxins and drugs in the digestive system, preventing them from being absorbed into the bloodstream.
   • Industrial Processes: Activated charcoal is used in various industrial processes, such as gas purification, solvent recovery, and chemical filtration.
5. Regeneration: Activated charcoal can be regenerated and reused by heating it to high temperatures to desorb the adsorbed substances. This process restores its adsorption capacity, making it a cost-effective option for many applications.