Q. Consider the following substances :

1. Ethanol
2. Nitroglycerine
3. Urea

Coal gasification technology can be used in the production of how many of them? (UPSC Prelims 2025)
Answer: All the three
Notes: The correct answer is [C] All the three. Coal gasification is a process that converts coal into synthesis gas (syngas)—a mixture of carbon monoxide, hydrogen, and carbon dioxide—which serves as a versatile building block for various chemicals.

• Urea (Correct): This is the most common application of coal gasification in India. Syngas is processed to produce ammonia (NH₃), which is then reacted with carbon dioxide (CO₂) to manufacture urea, a widely used nitrogenous fertilizer.
• Ethanol (Correct): Syngas can be converted into ethanol through two primary routes: chemical catalysis (the thermo-chemical route) or biological fermentation using specialized microorganisms. This allows for "coal-to-liquids" technology to produce biofuels.
• Nitroglycerine (Correct): Nitroglycerine is produced by nitrating glycerol. Coal gasification produces methanol, which can be further processed into synthetic glycerol. Additionally, the hydrogen from syngas is used to produce nitric acid (via ammonia), a key reactant in the production of explosives like nitroglycerine.

Historically, coal gasification has been used to produce Coal Gas for municipal lighting and heating, but modern "Clean Coal" technologies focus on high-value outputs like synthetic natural gas, methanol, and the industrial chemicals mentioned above.