$A$ solid cube and a solid sphere,both made of the same material,are completely submerged in water but at different depths. The sphere and the cube have the same surface area. The buoyant force is

$A$ cubical block of wood of specific gravity $0.5$ and a chunk of concrete of specific gravity $2.5$ are fastened together. The ratio of the mass of wood to the mass of concrete which makes the combination to float with its entire volume submerged under water is

Assertion $(A)$: $A$ helium-filled balloon does not rise indefinitely in the air but halts after a certain height.
Reason $(R)$: Viscosity opposes the motion of the balloon. Choose any one of the following four responses:

$A$ cube made of a material having a density of $0.9 \times 10^3 \ kg/m^3$ floats between water (density $1.0 \times 10^3 \ kg/m^3$) and a liquid of density $0.7 \times 10^3 \ kg/m^3$. What part of the cube is immersed in water?

$A$ small solid ball is dropped from a height above the free surface of a liquid. It strikes the surface of the liquid at $t = 0$. The density of the material of the ball is $500 \ kg/m^3$ and that of the liquid is $1000 \ kg/m^3$. If the ball comes momentarily to rest at $t = 2 \ s$,then the initial height of the ball from the surface of the liquid was ..... $m$ (neglect viscosity).

$A$ $0.5\ kg$ mass of lead is submerged in a container filled to the brim with water and a block of wood floats on top. The lead mass is slowly lifted from the container by a thin wire and as it emerges into air the level of the water in the container drops a bit. The lead mass is now placed on the block of wood. As the lead is placed on the wood,what happens to the water level in the container?