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प्रश्न
How do fishes and aquatic animals survive when the pond gets covered with thick ice?
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उत्तर
Water has an unusual physical property. When cooled, it first contracts in volume, as do other liquids, but at 4°C (maximum density), it starts expanding, and continues to do so till the temperature reaches 0°C, the point at which it freezes into ice.
The property of anomalous expansion of water enables marine life to exist in the colder regions of the world, because even when the water freezes on the surface, it is still liquid below the ice layer.
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संबंधित प्रश्न
Name the two gases from which water is formed. What is the chemical composition of these two gases in water ?
Match the statements in column A with that in column B.
| Column A | Column B |
| (a) deliquescent substance | (1) sodium bicarbonate |
| (b) hygroscopic substance | (2) magnesium chloride |
| (c) efflorestance substance | (3) conc. sulphuric acid |
| (d) substance causing temporary hardness | (4) washing soda |
Give balanced chemical equations to show the reaction between Magnesium and water.
How are clouds formed?
What is the effect of impurities present in the water on the melting point and boiling point of water?
Answer in your own words.
Why is there a shortage of water even though it occupies about 71% of the earth’s surface?
Give a balanced equation for the following conversion:
Sulphur dioxide to sulphurous acid using a neutral liquid.
Write a few slogans of your own on the topic “Save Water”
Look at the map of Tamilnadu showing annual rainfall and answer the questions given below
- Identify the districts that get only low annual rainfall in Tamilnadu.
- Identify the districts that get a medium annual rainfall in Tamilnadu.
- State the districts that enjoy high annual rainfall in Tamilnadu.
Match Column I with Column II
| Column I | Column II | ||
| (a) | Ground water | (i) | Solid form of water |
| (b) | Bawri | (ii) | Wastage of water |
| (c) | Snow | (iii) | Water management |
| (d) | Drip irrigation | (iv) | Small water |
| (e) | Leaking taps | (v) | Water table |
