Velocity of Efflux : Torricelli's Theorem

With what terminal velocity will an air bubble of diameter $0.8 mm$ rise in a liquid of density $900 kg m^{-3}$ and viscosity $0.15 Ns{m}^{-2}$? What will be the terminal velocity of the same bubble in water? Ignore density of air.

An air bubble (radius $0.4 mm$) rises up in water. Determine the terminal speed of the bubble. Density of air is negligible.

Two drops of equal radii are falling through air with a terminal velocity of $5 cm s^{-1}$. If they coalesce into one drop, what will be the terminal velocity of the new drop?