5.2. Radioactivity
A subsection of Physics, 5054, through 5. Nuclear physics
Listing 10 of 187 questions
Stars are formed inside a cloud of gas and dust in space. When a star forms, the cloud first becomes smaller as it collapses. State what causes the gas cloud to collapse. Eventually nuclear fusion occurs in the star. State two conditions required for nuclear fusion to occur in the star. 1. 2. When a large star explodes, nuclei of heavy elements are formed. One such nucleus is uranium-235 (23 2U). State the name and the number of each type of particle found in one nucleus of 23 2U. name of particle number found in nucleus name of particle number found in nucleus State one feature that is the same for the nuclei of all isotopes of uranium. A nucleus of 23 2U in a nuclear reactor can undergo nuclear fission. Describe the process of nuclear fission in a nuclear reactor. State one difference between nuclear fusion and nuclear fission. The nucleus of 23 2U is not stable. It decays by the emission of an alpha-particle (α) into a nucleus of thorium (Th). Complete the nuclear equation that represents this decay. 2U Th + 2 α Geiger and Marsden carried out an experiment to investigate the scattering of alpha-particles. shows a diagram of the apparatus that they used. vacuum thin gold foil fluorescent screen radioactive source beam of alpha-particles When an alpha-particle strikes the fluorescent screen a flash of light is emitted. On , mark with a letter P where most flashes occur on the screen. Describe what is seen on the other parts of the screen. State two conclusions about atoms of gold that resulted from this experiment.
5054_s19_qp_22
THEORY
2019
Paper 2, Variant 2
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The reaction that takes place at the centre of the Sun can be represented as 1p + 21 0n 2He. State the name of this type of reaction. The speed of light is 3.0 × 108 m / s. The mass of the helium nucleus (4 2He) produced is different from the total mass of the two protons and the two neutrons. The difference is 6.6 × 10–29 kg. Explain why energy is released during the reaction. Calculate the energy released in this reaction. State the formula used. energy =
5054_w08_qp_2
THEORY
2008
Paper 2, Variant 0
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Questions Discovered
187