Water drops are spherical in shape because of

Surface tension is the property of a liquid that causes its surface to behave like a stretched elastic membrane. It arises because molecules at the surface of a liquid experience a net inward pull from neighbouring molecules below and beside them, but not from above. This inward force causes the surface to contract to the smallest possible area.

For a given volume of liquid, the shape with the smallest surface area is a sphere. Therefore, when water forms small droplets (such as raindrops or drops on a waxy surface), surface tension pulls the water into a spherical shape.

The other properties do not explain the spherical shape:

• Polarity explains why water molecules attract each other (through hydrogen bonding), which contributes to surface tension, but polarity itself does not directly cause the spherical shape.
• Viscosity is the resistance of a liquid to flow. It affects how quickly water moves, not the shape of its droplets.
• Density is mass per unit volume and determines whether a substance sinks or floats, not the shape of droplets.

Exam tip: Surface tension explains several everyday observations: water forming spherical drops, insects walking on water surfaces, and a needle floating when placed gently on water.