Concept:Heating coal in the absence of air to produce useful by-products.
Explanation:Coal is a complex organic solid.
When it is heated strongly without air, it undergoes destructive distillation.
In this process, the coal decomposes into volatile products and a solid residue.
The volatile matter is collected and separated into coal gas, coal tar, and ammoniacal liquor.
The non-volatile solid residue left behind is coke.
For example, destructive distillation of one tonne of coal yields about
700kg of coke,
100 litres of ammoniacal liquor,
50 litres of coal tar, and
400m3 of coal gas.
Thus, the process is not steam distillation, liquefaction, or hydrolysis.
Answer:B. Destructive distillation