Question

Activated charcoal is used to remove colouring matter from pure substances. It works by:
A: oxidation
B: reduction
C: bleaching
D: adsorption

Answer 1

Hint: Activated charcoal is a fine, odourless and black coloured powder. The manufacture of activated charcoal makes it a strong adsorbent allowing it to bind effectively to atoms, molecules, or ions.

 Complete step by step answer:
Charcoal is made from wood, coal, or other substances. It becomes "activated charcoal" when high temperatures combine with a gas or activating agent to increase its surface area. Activated charcoal is the most commonly used adsorbent, is mostly known as the universal antidote. The large surface area of the charcoal adsorbs the toxicant, thereby reducing or restraining systemic absorption. It has been found that activated charcoal exhibits an antibacterial effect also by absorbing harmful microbes from wounds.
It has been observed that the surface of a solid (or liquid) has the capability to attract and restrict the molecules of other immiscible phases with which it is brought into contact. These molecules remain at the surface and do not go deeper into the bulk. This tendency of accumulation of molecular species at the surface in the bulk of a solid (or liquid) is termed as adsorption.
Therefore, activated charcoal is used to remove colouring matter from pure substances by (D) adsorption.

Note:
Activated charcoal is a form of carbon processed to have small or low-volume pores that increments the surface area available for adsorption or chemical reactions. One teaspoon full of activated charcoal has even more surface area than a football field.