\nSurface tension is a property of the surface of a liquid that allows it to resist an external force due to the cohesive nature of water molecules. It causes liquid surfaces to behave like stretched elastic membranes.
\nA) Nearly spherical drop of rain: Surface tension minimizes the surface area of the liquid, and a sphere has the minimum surface area for a given volume. This is a direct result of surface tension.
\nB) Capillary rise: This phenomenon, where a liquid rises in a narrow tube, is caused by the combined effects of surface tension and adhesion between the liquid and the tube walls. Surface tension contributes to the upward force.
\nC) Removal of dirt by soap or detergent: Soaps reduce the surface tension of water. This reduced surface tension allows the water to wet fabrics and dirt particles more effectively, helping in their removal. While it involves the *change* in surface tension, the ability to remove dirt in this way is linked to the surface properties facilitated by the detergent’s effect on surface tension.
\nD) Flow of a liquid: The bulk flow of a liquid (like water flowing in a pipe or a river) is driven by pressure differences or gravity, and it is resisted by viscosity. Surface tension primarily affects the liquid-air interface and phenomena occurring there (like drop formation, ripples), but it is not the fundamental cause or main characteristic of the bulk flow itself.
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