Question

Ice formed over lakes has
A. Very high thermal conductivity and helps in further ice formation
B. Very low conductivity and retards the further formation of ice
C. It permits quick convection and retards the further formation of ice
D. It is a very good radiator

Answer 1

Hint: We know that water exists in three states- solid, liquid, and gas. The solid form is known as ice and the gaseous form is water vapour. when a certain temperature is attained the change of state takes place. When the state changes, the temperature of the system will not change and this unique property plays a very important role in the existence of life on this planet.

Complete step by step solution:
The unique property of water is that it starts freezing from the top to the bottom, while most other substances freeze from the bottom to the top. This is the reason why the water allows the ice to float on top of the water. When the temperature starts decreasing, volume decreases, and as a result, the density of the substance increases but water shows anomalous behaviour.

Water has weird anomalous behaviour in the temperature range of \[0 - {4^0}C\]. When we start cooling any liquid, as we approach its freezing point, the density of the fluid increases until it becomes a solid. But, for water, we find that the max density is at \[{4^0}C\] instead of \[{0^0}C\] (its freezing point).

Due to this when the water in a water body starts freezing, the frozen solid part floats on the liquid since it's lighter. This solid chunk of ice at \[{0^0}C\] acts as an insulator, keeping the water below at and preventing it from freezing. This is the reason why a lot of aquatic life in colder countries is able to survive even during winter when the atmospheric temperature goes below freezing.

Hence, option B is the correct answer.

Note: If this anomalous behaviour didn't exist, like all other liquids, water would have started freezing from bottom to top. Due to this, the possibility of aquatic beings surviving would be zero since they would be frozen over. This would have been the case in most of the regions beyond the Arctic and Antarctic circles. Hence there would have been no possibility of aquatic life existing in these areas and the polar regions would have been fully filled with solid ice permanently.