Final answer:
Cube 1 has a greater density, as both cubes have the same mass but Cube 1 has half the volume, resulting in a larger density value when calculated with the formula D = m/V.
Step-by-step explanation:
If two cubes have the same mass but one cube has half the volume as the other, the cube with the smaller volume would have a greater density. The formula for density is D = m/V, where D is density, m is mass, and V is volume. Since both cubes have the same mass, the cube with half the volume will result in a larger value for density when we divide the mass by this smaller volume.
Therefore, the correct answer to which cube has a greater density is: 1) Cube 1.