The excess pressure inside a soap bubble is equal to an oil column of height $3 \mathrm{mm}.$ The total surface area of the soap bubble in contact with air will be (given, density of oil $=0.9 \mathrm{g} {\mathrm{cm}}^{-3},$ surface tension of soap solution $=0.03 \mathrm{N} {\mathrm{m}}^{-1}$ and $\mathrm{g}=10{ \mathrm{ms}}^{-2}$)

An incompressible liquid is flowing through a horizontal pipe as shown in figure. The magnitude of velocity $v$ is

A container filled with a liquid of density $4\rho$ as shown in the figure. The velocity of efflux through orifice is ( $\rho$ is density of water and $\mathrm{g}=10{ \mathrm{m} \mathrm{s}}^{-2}$)

An ideal liquid is flowing through the horizontal tube as shown in figure. If areas of cross-section of end $A$ and $B$ are $2{ \mathrm{mm}}^2$ and $4{ \mathrm{mm}}^2$ respectively and velocity of liquid at end $A$ is $4 \mathrm{m} {\mathrm{s}}^{-1}$ then velocity of liquid at end $B$ will be