The spherical shape of a rain-drop is due to

On what factors does the value of surface tension depend? Explain.

The unit of surface tension in the $SI$ system is

$A$ liquid is coming out from a vertical tube. The relation between the weight of the drop $W$,surface tension of the liquid $T$,and radius of the tube $r$ is given by,if the angle of contact is zero.

Soap helps in cleaning clothes,because

Two pieces of glass plates placed one upon the other with a little water in between them cannot be separated easily because of: