Question:
Lakes and ponds freeze at the top surface with water below. This phenomenon is due to
Lakes and ponds freeze at the top surface with water below. This phenomenon is due to
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Water is most dense at $4^\circ$C:
- Cold water ($<4^\circ$C) floats
- This is why lakes freeze from top, not bottom
Updated On: Apr 30, 2026
- high pressure at their bottom
- low pressure at their bottom
- the maximum density of water at $4^\circ$C
- the maximum density of water at $0^\circ$C
- elevation of freezing point of water
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The Correct Option is C
Solution and Explanation
Concept:
Water has maximum density at $4^\circ$C. This leads to an unusual behavior during cooling.
Step 1: Understand cooling of water.
As water cools from higher temperatures to $4^\circ$C, its density increases and it sinks.
Step 2: Behavior below $4^\circ$C.
When water cools below $4^\circ$C, it becomes less dense and rises to the surface.
Step 3: Formation of ice.
Surface water reaches $0^\circ$C and freezes, while denser $4^\circ$C water remains below.
Step 1: Understand cooling of water.
As water cools from higher temperatures to $4^\circ$C, its density increases and it sinks.
Step 2: Behavior below $4^\circ$C.
When water cools below $4^\circ$C, it becomes less dense and rises to the surface.
Step 3: Formation of ice.
Surface water reaches $0^\circ$C and freezes, while denser $4^\circ$C water remains below.
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