Answer: Less work is done in immersing the vessel with the opening.
Explanation:
During the immersion, a constant force F1 = Vd acts on the vessel without the opening, where d is the density of the water and V the volume of the vessel. During the immersion of the other vessel, the water will enter it, displacing the air. Hence the volume of the water displaced by the vessel will decrease, as will the buoyancy F2. Consequently, the work done against this force will, at any instant, be less than the work done against the force F1.
