Question

The size of what did Rutherford’s Scattering Experiment help in determining?
A. Nucleons
B. Electron
C. Atom
D. Nucleus

Answer 1

Hint: Remember that in Rutherford’s $\alpha$ray scattering experiment, the gold foil did not deflect nearly as many $\alpha$rays as it was expected to. What major conclusion did Ernest Rutherford draw from this experiment?

Complete step-by-step answer:
Ernest Rutherford was interested to know how the electrons were arranged within an atom. To help satisfy this curiosity, Rutherford designed an experiment. In this experiment, fast moving alpha ($\alpha$)-particles were made to fall on a thin gold foil.
He selected a gold foil because he wanted as thin a layer as possible. This gold foil was about 1000 atoms thick.
$\alpha$-particles are doubly-charged helium ions ($H{{e}^{+2}}$). Since they have a mass of 4µ, the fast-moving $\alpha$-particles have a considerable amount of energy.
It was expected that $\alpha$-particles would be deflected by the sub-atomic particles in the gold atoms. Since the $\alpha$-particles were much heavier than the protons, he did not expect to see large deflections. But, the $\alpha$-particle scattering experiment gave completely unexpected results which flabbergasted most scientists from around the world.
He observed that most of the $\alpha$-particles passed straight through the gold foil without any deviation.
Some of the $\alpha$-particles were deflected by the foil by some angles and about one out of every 12,000 $\alpha$-particles appeared to completely rebound off of the foil and retrace its original path.
As a result of this experiment, Rutherford then drew the following conclusions:
Most of the space inside the atom is empty as most of the $\alpha$-particles passed straight through the gold foil without getting deflected.
Very few particles were deflected from their path, indicating that the positive charge of the atom occupies very little space.
A very small fraction of $\alpha$-particles was deflected by very large angles, indicating that all the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.
This conclusion resulted in the idea that the nucleus was about $10^{-5}$ times the size of an atom, making it an absolutely minuscule structure.
Therefore, the answer to this question is d) Nucleus.

NOTE: Be very careful of the particular of both the question and the experiment’s conclusions before giving a definitive answer as this experiment was only concerned with the size of the nucleus itself and not the sub-atomic particles inside it.
Therefore, presuming nucleons to be the answer to this question would be very incorrect.