Water drops are spherical in shape because of

Step 1: Analyze the question We are asked why a free-falling water drop takes a spherical shape. This is about a property of liquids, specifically how molecules at the surface behave.

Step 2: Explain the concept

• Molecules inside a liquid are pulled equally in all directions by their neighbours (cohesive forces), so the net force is zero.
• Molecules at the surface have neighbours only below and beside them, so they are pulled inward. This creates a "skin-like" effect called surface tension.
• The liquid tries to minimise its surface area, because that gives the lowest surface energy.
• For a given volume, a sphere has the smallest surface area of any shape. So the drop becomes spherical.

Step 3: Check each option

• A. Polarity: Water is polar, and this causes hydrogen bonding. That is the origin of the strong cohesion, but polarity is not the direct reason for the shape. It explains why water has high surface tension, not the spherical shape itself.
• B. Viscosity: This is resistance to flow. It affects how fast a liquid moves, not its shape.
• C. Density: This is mass per unit volume. It does not determine shape.
• D. Surface tension: It makes the liquid minimise its surface area, giving a sphere. ✔

Step 4: Answer The correct option is D. surface tension.

Tip: Remember "Smallest surface area = sphere = surface tension." The same idea explains why small mercury droplets are round, why soap bubbles are spherical, and why some insects can walk on water. In JAMB, if a question asks about the shape of drops or bubbles, think surface tension first.