A wooden cube floating on water supports a mass m=0.2kg on its top.When the mass is removed,the cube rises by 2 cm.the side of cube is-

cube is floating, therefore
weight of liquid displaced = weight of cube
let  the volume of liquid displaced = V
and density of liquid = ρ
and mass of cube = M
then

if liquid is water then ρ = 1000 kg/m³   

                              l  =  0.02 m (given)

                              m= 0.2 kg (given)

putting these value we get a= 0.1 m

                                        = 10 cm