Question

In very cold places when the temperature becomes very low the surface of lakes freezes while the water inside does not as a result fish and other animals can still live in the lake can you tell by the water inside the lake does not freeze

Answer 1

${ \rm{ \large \underline \bold{Answer}}}$

This process is known as Anomalous expansion of water. In cold weather, when the atmospheric temperature starts falling below 0°C, water at the surface of a pond initially at temperature above 4°C, begins to radiate heat to the atmosphere, so the temperature of the water near the surface starts falling. When the temperature of the water falls below 4°C, water contracts and density increases and therefore it sinks to the bottom. This continues till temperature of the entire water reaches to 4°C result in the expansion of water. Now, further cooling of top layer below 4°C results in expansion of water and so it's density decreases. As, a result water doesn't stink further, but it remains on the surface of the water. When the temperature of atmosphere falls below 0°C, water on the surface loses further heat to the atmosphere and gradually freezes into ice, but water below the ice in contact with it will be at 0°C. Since, ice is a poor conductor of heat, so ice now prevent the flow of heat from water of pond to the atmosphere. Thus, temperature of water in contact with ice is at 0°C, while the temperature of water layers below the ice gradually increase to 4°C, as a result fish and other aquatic creatures remain alive in water of the pond though the surface of the pond has been freeze.

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$\large \underline \mathfrak{Extra \: information}$

Anomalous expansion of water is the unusual expansion of water when it is cooled from 4°C to 0°C. Normally all substances contracts on cooling but, water expands thus it is called unusual.

Answer 2

$\mathtt{\huge{\underline{\red{Question\:?}}}}$

In very cold places when the temperature becomes very low the surface of lakes freezes while the water inside does not as a result fish and other animals can still live in the lake can you tell by the water inside the lake does not freeze.Give Reason.

$\mathtt{\huge{\underline{\green{Answer:-}}}}$

It is due to the Anomalous expansion of water of lake. In extremely cold climate, the water reaches a very low temperature which is freezing point.

We know that the core of earth is very hot & as deep we go the temperature is high & causes suffocation inside water which results the hot springs & natural geysers.Although the atmospheric temperature is low the pressure inside water keeps its temperature maintain like "if we keep hot water in freezeer only above surface freezes & inside took a lot of time to freeze. Lakes are very deep and consist a lot of water. Lakes require a very low temperature to freeze which is imaginary temperature it's concluded by "Vant Hoff law".This is the reason why the water freeze on surface not in depth.

If we talk about aquatic life, they get oxygen by the aquatic plants. At the time, oxygen amount but it's enough for survival of aquatic animals.

$\mathcal{\large{\fbox{\purple{Anomalous\:Expansion:-}}}}$

It is an abnormal property of water whereby it expands instead of contracting when the temperature goes from 4°C to 0°C, and it becomes less dense.

$\mathcal{\large{\fbox{\pink{Vant\:Haff\:Law :-}}}}$

At constant temperature the osmotic pressure (⊓) of a delute solution is directly proportional to its molar concentration (C) or inversely proportional to volume (V) of the solution.

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