Two soap bubbles of radii ${r_1}$ and ${r_2}$ equal to $4 \,cm $ and $5 \,cm $ are touching each other over a common surface ${S_1}{S_2}$ (shown in figure). Its radius will be ....... $cm$

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

A spherical soap bubble of radius $3\,cm$ is formed inside another spherical soap bubble of radius $6\,cm$. If the internal pressure of the smaller bubble of radius $3\,cm$ in the above system is equal to the internal pressure of the another single soap bubble of radius $r\,cm$. The value of $r$ is.......

Write the equation of excess pressure (pressure difference) for the bubble in air and bubble in water.

A hot air balloon is a sphere of radius $8$ $m$. The air inside is at a temperature of $60^{°}$ $C$. How large a mass can the balloon lift when the outside temperature is $20^{°}$ $C$ ? Assume air is an ideal gas, $R = 8.314\,J\,mol{e^{ - 1}},1\,atm = 1.013 \times {10^5}{P_a},$ the membrane tension is $= 5\,N/m$.

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