Combustion and Flame class 8 worksheets with answers
Combustion and Flame
This worksheet is for Grade 8 Science, comprising the topic of Combustion and Flame. It will help students develop a better understanding of Combustion and Flame.
After completing this worksheet, students would be easily able to answer the following:
- List some conditions under which combustion occurs.
- Explain how the usage of compressed natural gas (CNG) in automobiles has helped to minimise pollution in our cities.
- Give a comparison between LPG and wood as fuels.
1. List conditions under which combustion occurs.
The following are the conditions under which combustion occurs:
- The presence of oxygen, a combustion supporter.
- Attaining the desired ignition temperature.
- The presence of combustible material.
2. Explain how the usage of compressed natural gas (CNG) in automobiles has helped to minimise pollution in our cities.
The usage of compressed natural gas (CNG) in cars has resulted in significant reductions in pollution in our cities in the following ways:
- When compared to other petroleum-based fuels like gasoline and diesel, compressed natural gas (CNG) is a clean fuel that produces no smoke when burned.
- For automobiles to run, petroleum fuel is burnt.
- The combustion of fuel leaves unburnt carbon particles in the air, along with carbon monoxide (CO) – a poisonous and harmful gas.
- Breathing CO causes headache, dizziness, etc.
- CNG burns completely leaving no harmful residue.
3. Give a comparison between LPG and wood as fuels.
| LPG | Wood |
| It is a gaseous fuel. | It is a solid fuel. |
| Fuel with a higher calorific value (55000 kJ/kg). | Fuel with lower calorific value (17000kJ/kg – 22000 kJ/kg). |
| It leaves no residue after being burned. | It leaves ash as residue after being burned. |
| It causes less pollution and is easy to store. | It causes more pollution, and its storage requires a lot of space. |
| Its transportation is easy in cylinders (or pipelines). | Its transportation is difficult. |
1. Fill in the blanks:
- Burning of _______ and _______ causes pollution of air.
- ________ is a liquid fuel, which is used in homes.
- Before the fuel starts burning, it must be heated to its _________.
- Oil-fueled fires are uncontrollable by _________.
2. State True or False:
- Because it is made up of oily carbon, soot created by burning is not toxic to us.
- CNG means ‘Compressed Natural Gas’.
- Combustion requires the presence of air.
- The wick in a candle serves as the source of heat and light.
3. Match the following:
| ‘A’ | ‘B’ |
| Gobar gas | Burning of fuels |
| Fire extinguisher | Cow dung |
| Petrol | CO2 |
| Combustion | Combustible substance |
| Fossil fuel | Petroleum |
Combustion and flame class 8 PDF worksheets with answers
combustion and flame class 8 worksheets with answers – PDF
ANSWER
1.
- Wood, coal
- Liquefied Petroleum Gas (LPG)
- Ignition temperature
- Water
2.
- False
- True
3.
- True
- False
| ‘A’ | ‘B’ |
| Gobar gas | Cow dung |
| Fire extinguisher | CO2 |
| Petrol | Petroleum |
| Combustion | Combustible substance |
| Fossil fuel | Burning of fuels |
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