Answer:
The fraction of the volume of the atom that is taken up by the nucleus is
.
The density of a proton is
.
Explanation:
Diameter of the atom ,d = 2.50 Å
Radius of the atom ,r = 0.5 d=0.5 × 2.50 Å = 1.25Å
Volume of the sphere= 
Volume of atom = V
..[1]
Diameter of the nucleus ,d' =
Radius of the nucleus ,r' = 0.5 d'=
Volume of nucleus = V'
..[2]
Dividing [2] by [1]



The fraction of the volume of the atom that is taken up by the nucleus is
.
Diameter of the proton ,d = 
1 m = 100 cm
Radius of the proton,r = 0.5 d=
Volume of the sphere= 
Volume of atom = V

Mass of proton, m = 1.0073 amu = 

Density of the proton : d

The density of a proton is
.