Answer:
21.5 g/cm³
Step-by-step explanation:
We define density as mass / volume.
We have the mass of the Pt piece → 175.5 g
Therefore, we must find out the volume with the data of dimensions:
3.50 cm . 2.16 cm . 1.08 cm = 8.16 cm³
Density is 175.5 g / 8.16 cm³ = 21.5 g/cm³