In the observations of the experiment of scattering of Alpha-particle…

The correct answer is Option (2) → (A) and (C) only

Most alpha particles passed straight through the gold foil, and only a very few were turned back. Rutherford concluded that the atom is mostly empty space with a tiny, heavy, positive nucleus at its centre.

(A) the positive charge and the mass of the atom are concentrated at the center called the nucleus — Correct. Only a small, massive, positive core can turn an alpha particle back.

(B) there is positive charge centralized at one point of the size about \( 10^{-10}\,\mathrm{m} \) inside the atom — Incorrect. \( 10^{-10}\,\mathrm{m} \) is the size of the whole atom; the nucleus is about \( 10^{-15}\,\mathrm{m} \) to \( 10^{-14}\,\mathrm{m} \) across.

(C) the atom being electrically neutral, it must have negatively charged electrons moving around the nucleus in different orbits — Correct. The electrons balance the positive charge and revolve around the nucleus.

(D) the nucleus is small, electrons move around, there is no space left empty inside the atom — Incorrect. Since most alpha particles went through undeflected, most of the atom is empty space.

NCERT (2026-27):
Alpha-Particle Scattering and Rutherford’s Nuclear Model of Atom – “… In Rutherford’s nuclear model of the atom, the entire positive charge and most of the mass of the atom are concentrated in the nucleus with the electrons some distance away. The electrons would be moving in orbits about the nucleus just as the planets do around the sun. Rutherford’s experiments suggested the size of the nucleus to be about 10^–15 m to 10^–14 m. From kinetic theory, the size of an atom was known to be 10^–10 m, about 10,000 to 100,000 times larger than the size of the nucleus. … Thus, most of an atom is empty space.”