Question

All combustion reactions are always exothermic which occur in the presence of excess air or oxygen. Substances acting as fuels undergo combustion when heated. It is not necessary that a particular substance undergoing combustion may burn also. The human body is just like a furnace or machine in which various foodstuffs that we eat undergo combustion. They provide the desired energy needed for the body's function.
Why is L.P.G. preferred to coke as a fuel?

Answer 1

L.P.G. Vs Coke

L.P.G.	Coke
1. It does not cause pollution by burning.	.1. Coke produces a lot of smoke when burnt.
2. It does not produce any toxic gas on burning.	2. Burning of coke produces carbon monoxide $\left(\mathrm{CO}\right)$ which can be lethal in large quantities.
3. It can be transported by pipes easily.	3. Transportation of coke is relatively difficult and expensive.

Hence, L.P.G. is preferred over coke because it causes less pollution and is relatively easier to transport.