Here's how to calculate the number of moles of platinum:

1. Calculate the mass of platinum:

* Density = Mass / Volume

* Mass = Density * Volume

* Mass = 21.45 g/cm³ * 14.5 cm³

* Mass = 310.525 g

2. Calculate the number of moles:

* Moles = Mass / Molar Mass

* Molar Mass of Platinum (Pt) = 195.084 g/mol

* Moles = 310.525 g / 195.084 g/mol

* Moles ≈ 1.59 mol

Therefore, there are approximately 1.59 moles of platinum in 14.5 cm³.