1 mole of platinum has a mass of 195 g therefore 1 atom will have a mass of 195 g /(6.02 ×10^23) = 3.239 × 10^-22 g Density is given by dividing mass by volume, thus to get volume, mass is divided by density. The volume = (3.239 × 10^-22)/21.4 = 1.514 × 10^-23 cm³ But volume of a sphere is given by 4/3πr³ Therefore, r³ = 3.6129 × 10^-24 r = ∛(3.6129 × 10^-24) = 1.534 × 10^ -8 cm Therefore, the radius of the platinum atom is 1.534 × 10^-8 cm
