We know,Radius of nucleus, r=r0A31where, A= mass number∴ Volume (v)=34πr3=34πr03⋅A∴v∝A∴ Volume is directly proportional to mass number.We know,density(d)=vm=34πr03(A1/3)3zmp+(A−z)mN=34πr03Azmp+Amp−zmp[∵mp≃mN]=34πr03AAmp=34πr03mp∴ Density of nucleus is independent of mass number.