Question

why does only the top layer of water freeze

Answer 1

Answer:

This is because water is most dense at 4 degrees Celsius so when it cools on the top it sinks and “warmer” water rises. Once this process stops the ice that forms on the top is less dense than the water so it floats.

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Answer 2

Question:-

why does only the top layer of water freeze

AnsWeR:-

In order for water to freeze, it must reach a temperature of 0oC . This occurs at the surface of a lake, which is why it freezes. However, water, being a special molecule, expands when it freezes, rather than contracts, meaning that the ice on top of the lake is less dense than the water underneath it