Assuming that the proton is in the shape of the sphere, let's calculate first its volume in units of cm³:
Volume of sphere = 4/3*πr³
Volume of sphere = 4/3*π{[(1.0×10⁻¹⁵ m * 100 cm/1m)]/2}³
Volume = 5.236×10⁻⁴⁰ cm³
The density is then equal to:
Density of proton = 1.0073 g/5.236×10⁻⁴⁰ cm³
Density = 1.924×10³⁹ g/cm³