Surface of the lake is at $2°C$ . Find the temperature of the bottom of the lake..... $^oC$
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(c) A lake cools from the surface down. Above $4^\circ C,$ the cooled water at the surface flows to the bottom because of it’s greater density.
But when the surface temperature drops below $4^\circ C$ (here it is $2^\circ C$), the water near the surface is less dense than the warmer water below.
Hence the downward flow ceases, the water at the bottom remains at $4^\circ C$ until nearly the entire lake, is frozen.
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