Question

Two needles are floating on the surface of water. A hot needle when touches water surface between the needles, then they move:

• A. Closer
• B. Away
• C. Out of the liquid
• D. Into the liquid

Answer 1

Answer: (B)

Away

A needle(greased) floats on water due to the phenomena of surface tension.The phenomenon wherein the free surface of a liquid acts as a stretched elastic membrane in order to possess minimum surface area is called surface tension. Consider two needles floating on water and we introduce a hot needle in between touching the water surface. As we increase the temperature the surface tension decreases that means the molecular interaction between the molecules decreases so the two needles moves away from each other.