Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens?

Question

A. The insects actually use their wings to hover slightly above the water's surface and they only skim it with their feet
B. The insects' feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water's surface
C.The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together
D. The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next

Answer 1

The best explanation for why small insects can walk across the surface of calm water is:

C. The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together.

This phenomenon is primarily due to surface tension, which is caused by the hydrogen bonds between water molecules. Smaller insects, such as water striders, are light enough that the force they exert on the water's surface when they place their feet down does not exceed the strength of these hydrogen bonds, allowing them to walk on the surface without sinking.