1718_H2_Nuclear_Physics_tutorial_with_soln

9749 H2 Physics Tutorial Nanyang Junior College 1 Chapter 20 NUCLEAR PHYSICS Self-Attempt Questions 1 (a) The figure below shows three alpha particles approaching a heavy stationary nucleus N. (i) Complete the diagram to show the paths of alpha particles as they pass by, and move away from N. (Particle C shows most deflection, follow by B, then A) (ii) The nucleus N could be one of several different isotopes of gold. 1 State what is meant by the term isotope. Isotopes are nuclei of atoms of a particular element containing the sa me number of protons but different number of neutrons. 2 Suggest, with an explanation, whether different isotopes of gold would give rise to different deviations of a particular α-particle. All isotopes of gold have the same number of protons, hence the same charge. There will be no difference in the deviations of the α-particle. (b) Classical experiments on alpha particle scattering were performed by Rutherford, Geiger and Marsden. State the experimental observation obtained from such experiments that proves that (i) the nucleus is small, Most of the alpha particles pass straight through the gold foil without being deflected. This shows that the nucleus is small and the atom is largely empty space.

9749 H2 Physics Tutorial Nanyang Junior College 2 (ii) the nucleus is massive and charged. Some alpha particles were scattered significantly and a very small number (about 1 in 8000) were deflected by more than 90°. This shows that the nucleus is positively charged, and that the nucleus is massive with the mass of the atom concentrated at the nucleus. 2 State what is meant by (a) relative atomic mass, The relative atomic mass is the ratio of the mass of one atom of the substance to 1/12th the mass of a carbon-12 atom. (b) nuclear binding energy. The nuclear binding energy of a nucleus is define d as the energy needed to completely separate the nucleons in the nucleus. (It is also defined as the energy released when a nucleus is formed from its constituent nucleons.) 3 The decay of 238 92U to 239 93Np by β-emission is not possible because A 239 93Np is not a stable isotope. B mass number cannot increase in a β-decay process. C atomic number cannot decrease in a β-decay process. D mass number and atomic number must both decrease in a β-decay process. Ans: B 4 Complete the following representations of nuclear transformation: (a) 9 12 4 6 1 0Be C n  (b) 13 14 6 7C p N    (c) 15 12 27 4 6N p C He  

9749 H2 Physics Tutorial Nanyang Junior College 3 5 The nuclide 238 92U decays to a final stable product 210 84Po through a series of radioactive nuclides. At each stage, an alpha or beta particle is emitted. Determine the number of alpha and beta particl