Two cubical blocks identical in dimensions float in water in such a way that the $1$st block floats with half part immersed in water and the $2$nd block floats with $3/4$ of its volume inside the water. The ratio of densities of the blocks is ..........

$A$ wax candle floats vertically in a liquid of density twice that of wax. The candle burns at the rate of $4\ cm/hr$. Then, with respect to the surface of the liquid, the upper end of the candle will:

$A$ $400 \ g$ solid cube having an edge of length $10 \ cm$ floats in water. How much volume of the cube is outside the water (in $cm^3$)? (Given: density of water $= 1000 \ kg/m^3$)

State Archimedes' principle.

$A$ boat having a length of $3\,m$ and breadth $2\,m$ is floating on a lake. The boat sinks by $1\,cm$ when a man gets on it. The mass of the man is ....... $kg$. (Take density of water $\rho = 1000\,kg/m^3$ and $g = 10\,m/s^2$)

$A$ hot air balloon is carrying some passengers and a few sandbags of mass $1 kg$ each,so that its total mass is $480 kg$. Its effective volume providing buoyancy is $V$. The balloon is floating at an equilibrium height of $100 m$. When $N$ number of sandbags are thrown out,the balloon rises to a new equilibrium height of $150 m$ with its volume $V$ remaining unchanged. If the variation of the density of air with height $h$ from the ground is $\rho(h) = \rho_0 e^{-\frac{h}{h_0}}$,where $\rho_0 = 1.25 kg m^{-3}$ and $h_0 = 6000 m$,the value of $N$ is: