The free surface of a liquid has a tendency to contract. This property is called ...... .

$A$ thin flat circular disc of radius $4.5 \,cm$ is placed gently over the surface of water. If the surface tension of water is $0.07 \,N \,m^{-1}$, then the excess force required to take it away from the surface is

Why are clothes easily washed by soap or detergent?

$A$ thread is tied slightly loose to a wire frame as shown in the figure. The frame is dipped into a soap solution and taken out,such that the frame is completely covered with a soap film. When the portion $A$ is punctured with a pin,the thread:

At which of the following temperatures,the value of surface tension of water is minimum in $^oC$?

$A$ small spherical droplet of density $d$ is floating exactly half immersed in a liquid of density $\rho$ and surface tension $T$. The radius of the droplet is (take note that the surface tension applies an upward force on the droplet).