Why does a body float or sink when placed on the surface of the water?

A jar is filled with two non-mixing liquids $1$ and $2$ having densities $d_1$ and $d_2$, respectively. A solid ball, made of a material of density $d_3$, is dropped in the jar. It comes to equilibrium in the position shown in the figure. Which of the following is true for $d_1$, $d_2$ and $d_3$?

A block of wood having a mass $15 \mathrm{kg}$ and dimensions $40\mathrm{cm} \times 30\mathrm{cm} \times 20 \mathrm{cm}$ is kept on a table-top, It is made to lie on the table-top in three ways with its sides of dimensions

(a) $40 \mathrm{cm} \times 30 \mathrm{cm}$

(b) $30 \mathrm{cm} \times 20 \mathrm{cm}$

(c) $20 \mathrm{cm} \times 40 \mathrm{cm}$
 

The pressure exerted by the wooden block on the table-top will be

A body weighs $600 \mathrm{gf}$ in air and $450 \mathrm{gf}$ in water. Find the volume of the body.

Give reasons: It is easier to swim in the sea than in the river.

Four students A, B, C and D wanted to determine the volume of an object by using an overflow can. Which student has made the correct set-up?

Give reasons: A body experiences more buoyant force on the earth than on the moon.