Which of the following property of water makes the raindrops to form roughly spherical structure?
- Aair resistance
- Batmospheric pressure
- Csurface tensionCorrect
- Dacceleration due to gravity
Solution
Concept
Surface tension makes a liquid take the shape with the least surface area, which is a sphere.
Step-by-step solution
1. A liquid surface acts like a stretched skin because of cohesion between molecules. This is surface tension. 2. Surface tension tries to make the surface area as small as possible. 3. For a fixed volume, the sphere has the smallest surface area. 4. So raindrops become roughly spherical. Answer is (C).
Explanation
Water molecules at the surface pull each other inward. This force, called surface tension, makes the drop take the shape with minimum surface area. That shape is a sphere.
Why the other options are wrong
A: Air resistance flattens large falling drops; it does not make them round. B: Atmospheric pressure acts equally from all sides and does not decide the shape. D: Gravity pulls the drop down and tends to distort it, not make it spherical.
Shortcut
Spherical drop, bubble or mercury globule means surface tension.
Common mistake
Choosing air resistance because the drop is falling through air.
Correct answer: C) surface tension