What is the pressure resulting from a gas filling a cubic box with 19.8 m length each side, and filled with 55 moles of gas atoms

Assume that our gas constant is R = 8.315 J/Kmol, and our gas is at room temperature, which is T = 300 K

2) a cubical block of stone is lowered at a steady rate into the ocean by a crane, always keeping the top and bottom faces horizontal. which one of the following graphs best describes the buoyant force b on this block as a function of time t if the block just enters the water at time t = 0 s?