While the block hovers in place, is the density of the block (top left) or the density of the liquid (bottom center) greater?

for the body to float, the density of the body must be less than or equal to the density of the liquid.

Explanation:

For a block to float in a liquid, the thrust of the liquid must be greater than or equal to the weight of the block.

Weight is

        W = mg

let's use the concept of density

        ρ_body = m / V

        m = ρ_body V

        W = ρ_body V g

The thrust of the body is given by Archimedes' law

        B = ρ_liquid g V_liquid

as the body floats the submerged volume of the liquid is less than or equal to the volume of the block

       ρ_body V g = ρ_liquid g V_liquid

       ρ_body = ρ liquid Vliquido / V_body

As we can see, for the body to float, the density of the body must be less than or equal to the density of the liquid.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.