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प्रश्न
You are provided with three watch glasses containing milk, petrol and mustard oil respectively. Suppose you bring a burning candle near these materials one by one, which material(s) will catch fire instantly and why?
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उत्तर
The watch glass containing petrol will catch fire instantly because its ignition temperature is very low. Also, petrol is an inflammable substance, i.e. it can easily catch fire with a flame.
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संबंधित प्रश्न
Which is the hottest part in the flame of candle ______.
Inner zone of flame : :______, outer zone of flame : :______
Name the unit in which the calorific value of a fuel is expressed?
The substances which gave very ______ ignition temperature and can easily catch fire with a flame are called ______ substances.
The substances which vaporise during ______ give flame.
Anu wants to boil water quickly in a test tube. On observing the different zones of the flame, she is not able to decide which zone of the flame will be best for boiling water quickly. Help her in this activity.
Match the following for the flame of a candle.
| Column A |
Column B |
Column C |
| (a) hottest part | (i) innermost zone of unburnt wax vapours | (x) blue |
| (b) moderately hot | (ii) middle zone of partial combustion | (y) black |
| (c) least hot | (iii) outer zone of complete combustion | (z) yellow |
Write True/False against the following statement and also correct the false statement.
The substances which vapourise during burning, give flame.
Match the following:
| 1. | Inner zone | a. | Yellow |
| 2. | Outer zone | b. | Borax powder |
| 3. | Middle zone | c. | Blue |
| 4. | Green flame | d. | Black |
Why is the candle flame straight?
