Oil spreads over the surface of water whereas water does not spread over the surface of the oil,due to

Why are small drops of liquid spherical in shape?

Two glass plates of area $10^{-2} \,m^2$ have a $10 \,cm$ thick water film between them. The surface tension of water is $70 \times 10^{-3} \,N/m$. The force required to separate the two glass plates from each other is (in $\,N$)

With the rise of temperature,the surface tension of a liquid

When water is heated,bubbles form at the bottom and detach to rise. Let the radius of the bubble be $R$. The bubble is in circular contact with the bottom of the container with a radius $r$. If $r \ll R$ and the surface tension of water is $T$,find the value of $r$ just before the bubble detaches from the container. (Density of water is $\rho_w$)

The surface tension of a liquid is $70 \, dyne/cm$. In $MKS$ system its value is