Two soap bubbles of radii $3r$ and $4r$ in contact with each other. The radius of curvature of the interface between bubbles is

A soap bubble, blown by a mechanical pump at the mouth of a tube, increases in volume, with time, at a constant rate. The graph that correctly depicts the time dependence of pressure inside the bubble is given by

The diameter of rain-drop is $0.02 \,cm$. If surface tension of water be $72 \times {10^{ - 3}}\,newton$ per metre, then the pressure difference of external and internal surfaces of the drop will be

Two soap bubbles have different radii but their surface tension is the same. Mark the correct statement

There is small hole in a hollow sphere. The water enters in it when it is taken to a depth of $40 \,cm$ under water. The surface tension of water is $0.07 \,N / m$. The diameter of hole is .......... $mm$

Two soap bubbles of radii $2 \,cm$ and $4 \,cm$ join to form a double bubble in air, then radius of curvature of interface is .......... $cm$