Explain What is the value of surface tension at critical temperature ?

Ans : the answer is Zero

but how ???????

please help !!

ANSWER

Since surface tension is the surface of the stretched film per unit increase in area provided that the temp. remains constant.

Mathematically, at critical temp. surface tension is equal to the perpendicular force acting on the free surface of liquid film.

Its S.I. unit is N/m & its formula is :- T=F/L 

The values of surface tension of differnt liquids at critical temp. at N/m are:-

1.) Mercury - 0.465 

2.) Water   - 0.075

3.) Soap Solution - 0.03

4.) Glycerine - 0.063

5.) Carbon Tetrachloride - 0.027

6.) Ethyl Alcohol - 0.022

Approved