Chapter 21, Problem 19A

Why do lakes and ponds freeze from the top down rather than from the bottom up?

To determine

To Explain: The lakes and ponds freeze from top rather than bottom up.

Explanation of Solution

Introduction: When one puts ice in a jar of water, the ice floats on the surface. It floats because the density of ice is less than the density of water.

If there is a lake or pond of liquid metal in place of water, then after freezing, the solid metal will not float because the density of liquid metal is less. But ice has lesser density than water due to which the ponds and lakes freeeze from top.

Conclusion:

Hence, the ice will float due to the less density.