Rutherford a Partical scattering experiment was responsible for discovery of:

Question

Accepted Answer

The correct option is (4):
The Rutherford alpha particle scattering experiment, often called the Gold Foil Experiment, was a pivotal moment in atomic theory. Before this experiment, the prevalent model was J. J. Thomson's "plum pudding" model, which suggested that atoms were uniformly distributed with positive charge and embedded electrons. However, Rutherford's experiment, where alpha particles were fired at a thin gold foil, yielded unexpected results. Most alpha particles passed straight through, indicating that atoms are mostly empty space. Crucially, a small fraction of alpha particles were deflected at large angles, and some even bounced back. This observation led Rutherford to conclude that a tiny, dense, positively charged center, which he named the "nucleus," must exist within the atom to cause such strong deflections. This discovery fundamentally changed our understanding of atomic structure, establishing the nuclear model of the atom.

The incorrect option is (1):
"e" represents the electron. Electrons were discovered by J. J. Thomson in 1897 through his cathode-ray tube experiments, well before Rutherford's scattering experiment. Rutherford's experiment focused on the distribution of positive charge and mass within the atom, not the existence of electrons.

The incorrect option is (2):
"p" represents the proton. While the nucleus, discovered by Rutherford, contains protons, the proton itself as a distinct particle was not directly discovered by the alpha particle scattering experiment. Rutherford later named the positive particle in the nucleus the "proton" in 1920, but his initial experiment revealed the existence of the dense, positively charged nucleus as a whole.

The incorrect option is (3):
"n" represents the neutron. The neutron was discovered much later in 1932 by James Chadwick. Rutherford's model, based on his scattering experiment, focused on the positively charged nucleus and orbiting electrons; the existence of an uncharged particle within the nucleus was not inferred from his alpha scattering results.