question_answer

At which of the following temperatures, the value of surface tension of water is minimum?

A) \[4{}^\circ C\]                                   

B) \[25{}^\circ C\]

C) \[50{}^\circ C\]                 

D)        \[75{}^\circ C\]

Correct Answer: D

Solution :

The surface tension of water is 72 dyne/cm at\[{{25}^{o}}C\]. It would take a force of 72 dyne to break a surface film of water \[1\,\,cm\] long. The surface tension of water decreases significantly with temperature as shown in the graph below. Out of the given four options \[{{75}^{o}}C\] is the highest temperature, at which surface tension is lowest.