In the alpha-particle scattering experiment, a beam of alpha-particles is directed at a thin gold foil. Which of the following options correctly pairs an observation from this experiment with the conclusion drawn from it?
Observation: Most alpha-particles pass straight through the foil undeflected. Conclusion: The nucleus of the atom is positively charged.
Observation: A tiny fraction of the alpha-particles are deflected back by more than 90∘90^\circ90∘. Conclusion: Most of the mass and positive charge of the atom are concentrated in a tiny, dense nucleus.
Observation: Some alpha-particles are deflected through small angles. Conclusion: The atom contains a dense cloud of electrons.
Observation: No alpha-particles pass through the foil without being deflected. Conclusion: The atom is a solid, continuous sphere.
114 exam-style questions on CIE IGCSE Physics 5.1.1a Structure of the atom and ions. Each one has a worked solution and a mark scheme showing where the marks go.