CBSE Class 8 Science Combustion and Flame Worksheets with Answers - Chapter 6 - PDF
FAQs on CBSE Class 8 Science Combustion and Flame Worksheets
1. What is the ignition temperature?
The lowest temperature at which a substance can catch fire is termed its ignition temperature. Studies demonstrate that a combustible substance cannot burn in the air as long as its temperature is lower than its ignition temperature. You might have seen cooking oil catching fire when a frying pan is kept for long on a lit stove. Wood and kerosene can be taken as examples. Kerosene oil catches fire on being heated while wood does not. This clearly shows that the ignition temperature of the wood is higher than that of kerosene.
2. Can you describe the various zones of a flame?
Let us discuss the various zones of a flame. A flame is divided into 3 zones. These are:
The innermost is the dark zone which comprises the unburnt vapors of wax.
The middle or yellow zone is where incomplete combustion takes place. It is also known as the luminous zone of a flame.
The outermost zone of the flame is quite thin and blue. Complete combustion takes place here which is why it is known as the non-luminous zone.
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4. What is acid rain?
The burning of fossil fuels like coal and diesel releases many toxic gases like sulphur dioxide and other nitrogen oxides. These gases are extremely suffocating and corrosive. Petrol engines particularly emit high amounts of gaseous oxides of nitrogen. These oxides of sulphur and nitrogen dissolve in rainwater after their formation to form acids. Such rain is termed acid rain and it is very detrimental to crops, buildings, and soil. Vegetation can be destroyed due to acid rain.
5. Which gas acts as a fire extinguisher?
Carbon dioxide gas acts as a fire extinguisher. Carbon dioxide is heavier than oxygen and covers the fire like a blanket. As the fuel is no longer in contact with the fuel now, the fire dies down. This is why carbon dioxide is used to control fires in which electrical equipment and inflammable materials are involved. Water can be used only when things like paper or wood are on fire. CO2 is generally stored under high pressure in liquid form inside cylinders.
