Question 9
The following Table shows the total power shortage in India from 1991–1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.
| S. No. | Year | Shortage (%) |
|---|---|---|
| 1 | 1991 | 7.9 |
| 2 | 1992 | 7.8 |
| 3 | 1993 | 8.3 |
| 4 | 1994 | 7.4 |
| 5 | 1995 | 7.1 |
| 6 | 1996 | 9.2 |
| 7 | 1997 | 11.5 |
Power shortage graph is shown below:
Chapter Overview: Coal and Petroleum
This chapter covers the formation, properties, and uses of fossil fuels (coal, petroleum, natural gas). Coal formation through carbonisation and its three products (coke, coal tar, coal gas) are important. Petroleum refining by fractional distillation into seven major fractions is a frequently tested topic. The chapter emphasises conservation of these exhaustible resources.
Board Exam Weightage: 4-6 marks | Difficulty: Moderate
Key Formulas & Concepts
| Concept | Details |
|---|---|
| Carbonisation | Dead vegetation converted to coal under high temperature and pressure over millions of years |
| Fractional Distillation | Separation of crude petroleum into fractions based on different boiling points |
| CNG | Compressed Natural Gas, mainly methane (CH4); used as cleaner vehicle fuel |
| Petrochemicals | Chemicals derived from petroleum; used to make plastics, synthetic fibres, detergents |
Must-Know Concepts
- Coal, petroleum, and natural gas are fossil fuels formed from dead organisms over millions of years
- Fossil fuels are exhaustible/non-renewable resources
- Coke is used in steel manufacturing; coal tar yields dyes, paints, drugs; coal gas is used as fuel
- Petroleum fractions from top to bottom: LPG, petrol, kerosene, diesel, lubricating oil, paraffin wax, bitumen
- CNG is the cleanest fossil fuel (produces less pollutants)
- PCRA promotes petroleum conservation in India
Products of Coal
| Product | Nature | Uses |
|---|---|---|
| Coke | Tough, porous, black solid (almost pure carbon) | Steel making, metal extraction |
| Coal Tar | Thick black liquid | Dyes, drugs, explosives, perfumes, paints, road surface |
| Coal Gas | Gas | Fuel in industries; earlier used for street lighting |
Common Mistakes to Avoid
- Thinking fossil fuels are renewable (they take millions of years to form)
- Confusing the order of petroleum fractions in the distillation column
- Mixing up coal tar (liquid) with coal gas (gaseous)
- Thinking CNG and LPG are the same fuel
Scoring Tips
- Use a mnemonic for petroleum fractions: Lovely People Keep Dogs, Lovely Pets Behave
- Draw and label the fractional distillation column from memory
- Learn 5 everyday ways to conserve fossil fuels
- Remember: petroleum is called black gold due to its high value
Frequently Asked Questions
Q: How many marks does this chapter carry in the exam?
A: Approximately 4-6 marks in the annual exam.
Q: What question types are commonly asked?
A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
Q: Is this chapter important for competitive exams?
A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.