Match the LIST-I with LIST-IILIST-IPhysicistLIST-IIPioneering WorkA.J…

The correct answer is Option (4) → A-III, B-I, C-IV, D-II

Each physicist is linked with the discovery or model that marked a step in understanding the structure of the atom and its nucleus.

(A) J. J. Thomson — this matches (III) plum pudding model of the atom. After discovering the electron, Thomson pictured the atom as a sphere of uniformly spread positive charge with electrons embedded in it.

(B) A. H. Becquerel — this matches (I) Radioactivity. In 1896 he found that uranium salts emit radiation on their own, with no outside cause; this was the discovery of radioactivity.

(C) James Chadwick — this matches (IV) Neutron. In 1932 he identified the neutral radiation emitted when beryllium is bombarded with α-particles as a stream of neutrons.

(D) Ernst Rutherford — this matches (II) scattering of α-particles by atoms to investigate the atomic structure. The α-particle scattering experiment (with Geiger and Marsden) showed that the positive charge and almost all the mass of an atom are packed into a tiny nucleus.

NCERT (2026-27):
Introduction – “… The first model of atom was proposed by J. J. Thomson in 1898. … This model was picturesquely called plum pudding model of the atom.”

Introduction – “… Ernst Rutherford (1871–1937), a former research student of J. J. Thomson, was engaged in experiments on α-particles emitted by some radioactive elements. In 1906, he proposed a classic experiment of scattering of these α-particles by atoms to investigate the atomic structure.”

Discovery of Neutron – “… This hypothesis was verified in 1932 by James Chadwick who observed emission of neutral radiation when beryllium nuclei were bombarded with alpha-particles (α-particles are helium nuclei, to be discussed in a later section).”

Radioactivity – “A. H. Becquerel discovered radioactivity in 1896 purely by accident.”