Explain why the coin is able to float on top of the water in this glass.

Answer:

The coin is able to float on top of the water due to surface tension. Water molecules at the surface are more attracted to each other than to the air above, creating a cohesive 'skin' or tension. If the coin is light enough and placed carefully, this surface tension is strong enough to support the weight of the coin and prevent it from breaking through the surface and sinking.