Question

Assertion: Only one out of every 12000 alpha particles rebound in Rutherford’s experiment.
Reason: Most of the space in the atom is empty.
(A) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
(B) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
(C) Assertion is correct but Reason is incorrect.
(D) Both Assertion and Reason are incorrect.

Answer 1

We need to find out whether the assertion and reason are correct or incorrect. The above question is in reference to Rutherford Experiment. He proved that an atom consists of a tiny mass called nucleus which occupies only the space but accounts for more than 99% of the mass.

Complete step by step answer
The experiment demonstrates that an atom has a tiny and heavy nucleus. Rutherford designed an experiment to use the alpha particles emitted by a radioactive element as probes to the unseen world of atomic structure.
Since most of the alpha-particle went straight through the metal foil undeflected, it means that there must be very large empty space within the atom.
Since few of the alpha-particles were deflected from their original path through moderate angles, it was concluded that the whole of the + ve charge is concentrated and the space occupied by this positive charge is very small in the atom.
As the statements suggest, both the assertion and reason are correct but there is no dependence of assertion on reason.
So, we need to see from the above options, and select the correct option.
Thus, the correct answer is option B.

Note
The experiment in the history of the atom was performed by Ernest Rutherford, from New Zealand. In his famous gold foil experiment, Rutherford fired a thin beam of alpha particles at a very thin sheet of pure gold. Alpha particles are helium nuclei ($_{2}^{4}H{{e}^{2+}}$) and they are given off in various radioactive decay processes. In this case, Rutherford placed a sample of radium (a radioactive metal) inside a lead box with a small pinhole in it. Most of the radiation was absorbed by the lead, but a thin beam of alpha particles escaped out of the pinhole in the direction of the gold foil. The gold foil was surrounded by a detector screen that would flash when hit with an alpha particle. Based on Thomson's plum pudding model, Rutherford predicted that most of the alpha particles would pass straight through the gold foil. This is because the positive charge in the plum pudding model was assumed to be spread out throughout the entire volume of the atom.