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Name the products obtained and their uses when coal is processed in industry.
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Coal reserves are said to be enough to last for another hundred years. Do you think we need to worry in such case? Why or why not?
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Magnesium ribbon on burning in air produces
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The substance that does not burn with flame is ______.
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On placing an inverted tumbler over a burning candle, the flame extinguishes after some time. This is because of non-availability of
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The ______ temperature at which a substance catches fire is called its ______ temperature.
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The substances which gave very ______ ignition temperature and can easily catch fire with a flame are called ______ substances.
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The substances which vaporise during ______ give flame.
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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.
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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 |
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If you hold a piece of iron wire with a pair of tongs inside a candle flame or a Bunsen burner flame, what will you observe? Will it produce a flame?
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Write True/False against the following statement and also correct the false statement.
Middle zone is the hottest zone of a flame.
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Write True/False against the following statement and also correct the false statement.
The substances which vapourise during burning, give flame.
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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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Wild buffalo is an endangered species because
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Which one of the following changes may occur due to desertification?
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The places meant for conservation of biodiversity in their natural habitat are
- Zoological garden
- Botanical garden
- Wildlife sanctuary
- National park
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Which of the following feature is correct for a wildlife sanctuary?
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How are even small animals important in an ecosystem?
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Does soil erosion affect the fertility of soil? How?
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