Where is it easier to keep the body in air or water? Why?

In liquid. The buoyant (Archimedean) force acts in both liquid and gas. It is equal to the weight of a liquid or gas taken in the volume of a submerged body, but since the density of the liquid is orders of magnitude greater than the density of the gas, then the corresponding pushing force will be much greater. And the force of gravity of the body will decrease by the buoyancy force (since the direction of this force is opposite to the force of gravity), and the body will be easier to hold.