Question

The by-products of coal are obtained when coal is:

• A. cooled in absence of air.
• B. heated in absence of air.
• C. heated in presence of air.
• D. cooled in presence of air.

Answer 1

The correct option is B heated in absence of air.

Heating helps in separating the different materials which form the by-products of coal. The absence of air prevents oxidation and any chemical reaction of coal with it.

Therefore, coal should be heated in the absence of air in order to obtain the by-products. This process is called destructive distillation of coal.