Q13
2 marksShort AnswerSection A

Give two examples each of the following : (i) Renewable sources of energy (ii) Non-renewable sources of energy

Chemical Reactions and Equations
Exothermic Reactions and Energy Sources
Official Answer

Based on the chemical processes described in the text, examples of energy sources are:

(i) Renewable sources of energy:

  1. Sunlight: Used as an energy source for photosynthesis as shown in the reaction:

6CO2(aq)+12H2O(l)→SunlightC6H12O6(aq)+6O2(aq)+6H2O(l)6CO_2(aq) + 12H_2O(l) \xrightarrow{Sunlight} C_6H_{12}O_6(aq) + 6O_2(aq) + 6H_2O(l)

  1. Biomass (Vegetable matter): The text mentions the decomposition of vegetable matter into compost as an exothermic reaction, which is a form of bio-energy.

(ii) Non-renewable sources of energy:

  1. Coal: Mentioned in the burning of coal reaction:

C(s)+O2(g)→CO2(g)C(s) + O_2(g) \rightarrow CO_2(g)

  1. Natural Gas: Mentioned in the burning of natural gas (methane) reaction:

CH4(g)+2O2(g)→CO2(g)+2H2O(g)CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(g)

SunlightBiomassCoalNatural GasRenewableNon-renewable

Marking Scheme

  • 1Two examples of renewable sources (1 mark)
  • 2Two examples of non-renewable sources (1 mark)

Hint

Look for substances in the text that release heat upon burning or are used as energy inputs for reactions like photosynthesis.

Quick Oral Answer

Renewable sources like sunlight are inexhaustible, while non-renewable sources like coal and natural gas are depleted upon use. In the text, coal and natural gas are shown to release energy through exothermic combustion reactions.

Analysis & Explanation

Renewable sources are those that are replenished naturally over short periods, such as sunlight (used in photosynthesis) and biomass (vegetable matter). Non-renewable sources are finite and take millions of years to form, such as fossil fuels like coal and natural gas (methane), both of which are used in the text to demonstrate combustion and exothermic reactions.

Common Mistakes

  1. 1Confusing the decomposition of vegetable matter with a non-renewable process.
  2. 2Listing electricity as a primary source instead of the fuel used to generate it.

Interesting Facts

Respiration is also an exothermic process where glucose (from food) reacts with oxygen to provide energy to our cells.

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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 "Exothermic Reactions and Energy Sources" 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.