In the Geiger-Marsden α\alphaα-particle scattering experiment, a beam of α\alphaα-particles is directed at a thin gold foil.
Which of the following observations provides direct evidence that the positive charge and nearly all of the mass of an atom are concentrated in a tiny, dense region (the nucleus)?
A very small fraction of the α\alphaα-particles are deflected through angles greater than 90∘90^\circ90∘ back towards the source.
The vast majority of the α\alphaα-particles pass straight through the gold foil with little or no deflection.
Some α\alphaα-particles are absorbed by the gold atoms, causing them to emit beta radiation.
The α\alphaα-particles follow a continuously spiral path as they pass through the foil.
284 exam-style questions on CIE IGCSE Physics 5.1 The nuclear model of the atom, covering 5.1.1a Structure of the atom and ions, 5.1.1b Alpha-particle scattering, 5.1.2a Composition of the nucleus and isotopes, 5.1.2b Proton number, nucleon number and nuclide notation, and 5.1.2c Nuclear fission and nuclear fusion. Each one has a worked solution and a mark scheme showing where the marks go.