Question

Which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water's surface?

A. Covalent bonds between water molecules and the air above provide cohesion, which causes tiny bubbles to form under the feet of the insect.
B. Ionic bonds between molecules at the surface of the water provide an electric charge, which attracts the feet of the insect, keeping it on the surface.
C. Polar covalent bonds between molecules at the surface of the water provide adhesion, which supports the weight of the insect.
D. Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.

Answer 1

Insects can walk on water due to the high surface tension created by cohesion between water molecules, which is due to hydrogen bonding. This surface tension supports insects on water without breaking the surface.

The properties of water at an air-water interface that enable an insect to walk on water's surface can be attributed to the surface tension caused by cohesion among water molecules. Cohesion, the attraction between water molecules due to hydrogen bonding, generates a high surface tension on water. This allows insects, like the water strider, to walk on water without breaking the surface. While adhesion refers to the attraction between water molecules and different types of molecules, it is primarily the cohesive forces amongst the water molecules that give rise to surface tension.

Thus, the correct answer to the question is D. Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.