Question

Liquid drops assume spherical shape because:
A. A sphere has maximum surface area
B. A sphere has minimum surface area
C. A sphere is symmetrical in shape
D. None of these

Answer 1

Hint: Apply the following concept in this question - any element, particle or substance in nature has a tendency to remain in rest. Therefore, they mend themselves in such a configuration so as to gain the maximum stability.

Complete step by step answer:
Surface tension is defined as the tendency of liquid surfaces to shrink into the minimum surface area possible.
The free surface of a liquid drop tries to acquire a spherical shape because a drop always tends to acquire minimum surface area for least surface tension. The liquid drop tries to pull in all the liquid on the surface inside, towards its center.
Note that for given volume, the surface area of the sphere is minimum.
Now let us elaborate.
Molecules below the surface of a liquid are very much influenced by intermolecular attractions from all directions. Those present on the surface are attracted only towards the interior; these attractions pull the surface layer toward the center. The most stable situation is the one in which the surface area is minimum. Since, for a particular volume a sphere has the least possible surface area, therefore, the drops of liquid tend to assume spherical shapes.
For example –The small droplets of mercury on a grass surface is almost spherical, whereas the larger droplets get a little flattened due to the effects of gravity.
Therefore, we can conclude that the answer is – option (b), i.e. Liquid drops assume spherical shape because a sphere has minimum surface area.

Additional Information: It is because of surface tension that allows insects (usually denser than water) to float and slide on a water surface.

Note: The SI unit of surface tension is Newton per meter square. From the SI unit we can see that surface tension is a kind of ‘pressure’ between the water molecules.