Q12
2 marksShort AnswerSection A

List any four disadvantages of using fossil fuels for the production of energy.

Chemical Reactions and Equations
Fossil Fuels and Environment
Official Answer

The disadvantages of using fossil fuels for energy production include:

  1. Air Pollution: The combustion of fossil fuels (like coal and petroleum) releases acidic oxides of carbon, nitrogen, and sulphur. For example, the burning of coal is represented as C(s)+O2(g)→CO2(g)C(s) + O_2(g) \rightarrow CO_2(g).
  2. Global Warming: The release of large amounts of carbon dioxide (CO2CO_2) into the atmosphere enhances the greenhouse effect, leading to a rise in global temperatures.
  3. Acid Rain: Oxides of nitrogen and sulphur (such as SO2SO_2 and SO3SO_3 produced during combustion) react with water vapor in the atmosphere to form acid rain, which damages soil, water resources, and monuments.
  4. Non-Renewable Nature: Fossil fuels are exhaustible resources. They took millions of years to form and are being consumed at a rate much faster than they are being replenished.
air pollutionglobal warmingacid rainnon-renewableoxides of carbon, nitrogen, and sulphur

Marking Scheme

  • 1Mentioning air pollution/release of harmful oxides. (0.5 marks)
  • 2Mentioning global warming/greenhouse effect due to CO2CO_2. (0.5 marks)
  • 3Mentioning acid rain caused by sulphur and nitrogen oxides. (0.5 marks)
  • 4Mentioning that they are non-renewable/exhaustible. (0.5 marks)

Hint

Think about the gases released during combustion and whether these fuels will last forever.

Quick Oral Answer

Fossil fuels cause air pollution by releasing oxides of sulphur and nitrogen, contribute to global warming through CO2CO_2 emissions, cause acid rain, and are non-renewable, meaning they will eventually run out.

Analysis & Explanation

Fossil fuels are primarily composed of carbon and hydrocarbons. When they burn (an exothermic oxidation reaction), they release energy but also produce gaseous byproducts. While CO2CO_2 is a natural product of complete combustion, its excess leads to climate change. Impurities in fuels lead to SO2SO_2 and NOxNO_x gases, which are toxic and contribute to environmental degradation. As noted in the text, reactions like 2FeSO4(s)→HeatFe2O3(s)+SO2(g)+SO3(g)2FeSO_4(s) \xrightarrow{Heat} Fe_2O_3(s) + SO_2(g) + SO_3(g) demonstrate how sulphur oxides are generated, which mirrors the impurities found in low-grade coal.

Common Mistakes

  1. 1Only mentioning 'pollution' without specifying the types of gases or effects like acid rain.
  2. 2Confusing the greenhouse effect with ozone layer depletion.

Interesting Facts

Coal-fired power plants are the largest producers of CO2CO_2 emissions globally, contributing significantly to the 35+ billion tonnes of CO2CO_2 humans release annually.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2011?

This question carries 2 marks in the CBSE Class 10 Science 2011 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Chemical Reactions and Equations" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Fossil Fuels and Environment" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2011 paper?

This is a Short Answer question from Section A in the CBSE Class 10 Science 2011 paper.