The pressure inside an air bubble of radius $2 \mathrm{cm}$ formed $20 \mathrm{cm}$ below an open water surface is (Given surface tension of water $=70\times {10}^{-3} {\mathrm{Nm}}^{-1}$)

A sphere of radius $r$ is dropped in a liquid from its surface. Which of the following graphs is/are correct?

A cone of radius $R$ and height $H$, is hanging inside a liquid of density $\rho$ by means of a string as shown in the figure. If ratio of the force acting on the slant surface to that on the base by the liquid is $P : Q$ then value of $\left(P+Q\right)$ is _____. (Assume atmospheric pressure is zero and vertex of cone is just touching the liquid surface)

Four spheres of equal radii $R$ are arranged as shown in figure. All four spheres are in equilibrium. Given that ${\rho }_A=2\rho , {\rho }_B=4\rho , {\rho }_D=5\rho$ and spring constant $=k.$ If elongation produced in the spring is $\frac{N\pi \rho R^{3}g}{3k}$ then $N$ is _____.