What characteristic property of nuclear force explains the constancy of binding energy per nucleon (BE/A) in the range of mass number A lying 30 < A < 170?

(i)The approximate constancy of BE/A over most of the range is saturation property of nuclear force. In heavy nuclei, nuclear size > range of the nuclear force. So a nuclear sense approximately a constant number of neighbors and thus the nuclear BE/A levels off at high A. This saturation of the nuclear force (ii)The mass of the nucleus of the atom of the mass number A A= A a.m.u.= A × 1.660565 × 10⁻²⁷ kg The volume of the nucleus is 4πr³/3 = 4π/3(R₀A¹/³)³ = 4πR₀³/3A ∴Volume=4π/3(1.1 × 10⁻¹⁵)³ × Am³ Now the density of the nucleus=m/V; where m is mass and V is the volume of the nucleus. ρ=A × 1.660565 × 10⁻²⁷ / [4π/3(1.1 × 10⁻¹⁵)³ × A] =2.97 × 10¹⁷ kgm⁻³ Thus, we can see the density of the nuclei is independent of mass number and it is constant for all nuclei.