The radius of a soap bubble is increased from $\frac{1}{\sqrt{\text{π}}} \mathrm{cm}$ to $\frac{2}{\sqrt{\text{π}}} \mathrm{cm}$. If the surface tension of water is $30 \mathrm{dynes} {\mathrm{cm}}^{-1}$, then the work done will be

The figure shows a soap film in which a closed elastic thread is lying. The film inside the thread is pricked. Now, the sliding wire is moved out so that the surface area increases. The radius of the circle formed by elastic thread will

A long capillary tube of mass$\text{'}\pi \text{'}$ $\mathrm{gm}$, radius $2$ $\mathrm{mm}$ and negligible thickness, is partially immersed in a liquid of surface tension $0.1 \mathrm{N} {\mathrm{m}}^{-1}$. Take angle of contact zero and neglect buoyant force of liquid. The force required to hold the tube vertically will be $(g=10\mathrm{m} {\mathrm{s}}^{-2})$