Question

The mass no of iron nucleus is 56 the nuclear density is

Answer 1

according to rutherford's relations radius of nucleus = ro×A13 

ro = constant = 1.2×10−15 m

therefore r = 1.2×10−15 ×56−−√3r = 4.59 ×10−15 m
also,1u = 1.67×10−27 kg
55.85 
u = 9.327 ×10−26 kg 
= mass of nucleus of iron atomnuclear density
 = mass of nucleus of iron atomvolume of nucleus nuclear density

 = 9.327 ×10−26 kg43π×r3
 =9.327 ×10−26 kg43π×(4.59 ×10−15 )3 nuclear density = 4.851×1018 kg/m3


hope helps