Water does not freeze at the bottom of the lakes in winter because :
A
ice is a good conductor of hear
B
of anomalous expansion of water between $$4^oC$$ to $$0^oC$$
D
ice reflects heat and light
Correct option is C. of anomalous expansion of water between $$4^oC$$ to $$0^oC$$
lets look at the freezing process of water in lakes :
The top layer of water which is exposed to surrounding emits heat energy to the surrounding due to which temperature of water lower , if we divide the process in two parts:
$$T>4^oC$$ : when the temperature of top layer lowers its density increases so momentarily its density is more than densities of bottom layers therefore the top layer of water sinks down
$$T\leq 4^oC$$ : now when top layers emits heat its temperature lower but density decreases so it does not sinks down and remains at the top and when freezing process will start at $$0^oc$$ it will be from top to bottom.
The ice formed on the surface is less dense than water and floats at the water surface. This layer acts as an insulation layer which prevents contact between the water bulk and the freezing surrounding, thus preventing further freezing of water