18 Questions
What happens to the flame when a glass plate is placed over the chimney, as described in the text?
The flame flickers off due to lack of air.
What can be inferred about the role played by air in the process of burning, based on the text?
Air is essential for combustion.
Why does a piece of wood or coal require paper or kerosene oil to start burning, according to the text?
To provide an initial source of ignition.
What happens when a burning matchstick is brought near a piece of wood, as discussed in the text?
The wood requires an additional source of ignition to catch fire.
Is the sun's heat and light production considered a form of combustion, according to the text?
No, because it is caused by nuclear reactions.
Why does a candle burn freely in a chimney when air can enter from below, as mentioned in the text?
Because air is necessary for combustion.
What type of fuel vapourises during burning and gives flames?
Kerosene oil
Why does charcoal not produce a flame when burned?
It does not vapourise during burning
What causes the deposition of unburnt carbon particles on the glass plate/slide?
Luminous zone of the flame
In the non-luminous zone of the flame, what part is considered to be the hottest?
The portion just outside the flame
What is the circular blackish ring on the glass plate/slide a sign of?
Deposition of unburnt carbon particles
Why does the portion of the copper wire just outside the flame get red hot?
It is in direct contact with the flame
What are the characteristics of a good fuel?
Readily available, cheap, burns easily at a moderate rate, produces a large amount of heat
Why is there probably no ideal fuel?
Because no fuel fulfills all requirements for every use
Why does a goldsmith use the outermost zone of a flame?
To achieve complete combustion with the hottest part of the flame
What are the three zones of a candle flame?
Innermost unburnt zone, outermost complete combustion zone, middle partial combustion zone
Why should a fuel not leave behind any undesirable substances?
To avoid pollution and harmful effects on health
If you were asked to choose a fuel to boil water among cow dung, coal, and LPG, which would you prefer?
LPG because it is readily available and burns easily
Test your knowledge on the different zones of a candle flame and the characteristics of good fuels. Learn about the outermost zone of complete combustion (blue), moderately hot middle zone of partial combustion (yellow), and the least hot innermost zone of unburnt wax vapors (black). Explore the properties of fuels that make them effective for burning.
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