Final answer:
The student should multiply the density of the cube by its volume to find its mass. The correct mass of the cube is 8.0 grams.
Step-by-step explanation:
To determine the mass of an object, one can use the formula where mass is equal to the density multiplied by the volume. In this case, the density of the plastic cube is given as 2.0 g/cm³ and the volume of the cube is measured as 4 cm³. Therefore, to calculate the mass, the student should multiply the density by the volume.
The calculation would be as follows:
Mass = Density × Volume
Mass = 2.0 g/cm³ × 4 cm³
Mass = 8.0 g
Thus, the mass of the cube is 8.0 grams.