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प्रश्न
Explain the following
Fishes survive in ponds even when the atmospheric temperature is well below 0°C.
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उत्तर
The anomalous expansion of water helps preserve aquatic life during very cold weather. When temperature falls, the top layer of water in a pond contracts becomes denser and sinks to the bottom. A circulation is thus set up until water in the pond reaches its maximum density at 4°C. If the temperature falls further, then the top layer expands and remains on the top till it freezes. Thus, even though the upper layer are frozen, the water near the bottom is at 4°C and the fishes can survive in it easily.
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