If the radius of a soap bubble is four times that of another, then the ratio of their excess pressures will be

The excess pressure due to surface tension in a spherical liquid drop of radius r is directly proportional to

A soap bubble is blown with the help of a mechanical pump at the mouth of a tube. The pump produces a certain increase per minute in the volume of the bubble, irrespective of its internal pressure. The graph between the pressure inside the soap bubble and time $t$ will be-

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

The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be $75\, cm$ of $Hg$ and the density of water to be $1/10  $ of the density of mercury, the depth of the lake is ....... $m$

Pressure inside two soap bubbles are $1.02 \,atm$ and $1.05 \,atm$ respectively. The ratio of their surface area is .........