The phenomenon of surface tension relates to the elastic tendency of a fluid surface, allowing it to resist an external force. It arises due to the intermolecular forces among the molecules at the surface of a liquid.
The question asks at what condition the surface tension vanishes. Let’s analyze the options given:
- Absolute Zero Temperature: At absolute zero temperature, most physical motions cease, but it does not mean the surface tension would vanish. Therefore, this is not the correct answer.
- Transition Temperature: Transition temperature relates to changes like phase transitions, but not typically where surface tension becomes zero.
- Critical Temperature: This is the temperature above which a gas cannot be liquefied, regardless of pressure applied. As a fluid approaches critical temperature, the density of the liquid and its vapor becomes equal, eliminating the distinction between liquid and vapor phases. At this point, the surface tension is zero because there is no longer a surface boundary.
- None of the above: This option suggests that none of the previous options are correct, which is incorrect since surface tension does vanish at critical temperature.
Hence, among the options provided, the correct answer is "critical temperature."
Therefore, the surface tension vanishes at
\(T_c\) (Critical Temperature).