STATEMENT-1: The plot of atomic number (y-axis) versus number of neutrons (x-axis) for stable nuclei shows a curvature towards x-axis from the line of 45° slope as the atomic number is increased.
and
STATEMENT-2: Proton-proton electrostatic repulsions begin to overcome attractive forces involving protons and neutrons in heavier nuclides.
Official answer: A
Statement 1. Light stable nuclei have (the 45° line); heavier ones need more neutrons than protons, so the band of stability bends towards the neutron (x) axis. True.
Statement 2. The proton-proton Coulomb repulsion grows faster () than the short-range nuclear attraction, so extra neutrons are needed to hold heavy nuclei together. True, and this is the reason for the curvature.
(A)