Radioactivity Lecture 2
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Questions and Answers

What particles are β-particles identical to?

  • Electrons (correct)
  • Neutrons
  • Protons
  • Alpha particles

    • Which particle has the highest penetrating power?

  • Beta particles
  • Alpha particles
  • X-rays
  • Gamma rays (correct)

    • How does the ionising power of β-particles compare to α-particles?

  • Less than that of γ-rays
  • Equal to α-particles
  • More than α-particles
  • One-hundredth of that of α-particles (correct)

    • What is the primary reason γ-rays are considered weak ionisers?

    <p>The chances of photon-electron collisions are small</p> Signup and view all the answers

    What thickness of aluminum can stop β-particles?

    <p>1 cm</p> Signup and view all the answers

    Which of the following statements is true about α-particles?

    <p>They can ionize gas more intensely than β-particles</p> Signup and view all the answers

    What characteristic differentiates gamma rays from alpha and beta rays?

    <p>Gamma rays are a form of electromagnetic radiation</p> Signup and view all the answers

    Which particle travels about 10 times faster than α-particles?

    <p>Beta particles</p> Signup and view all the answers

    What is the nature of an α-particle?

    <p>He nucleus</p> Signup and view all the answers

    Which type of radiation has the highest penetrating power?

    <p>ϒ -- rays</p> Signup and view all the answers

    What material can effectively stop α-particles?

    <p>Paper or 0.01mm thick Al sheet</p> Signup and view all the answers

    Which technique is primarily used to visualize the tracks of α or β particles?

    <p>Cloud Chamber</p> Signup and view all the answers

    What primarily happens when radiation passes through an ionization chamber?

    <p>It ionizes gas molecules, forming positive ions and electrons</p> Signup and view all the answers

    How does the Geiger-Muller counter detect radiation?

    <p>By detecting the movement of argon ions to the cathode</p> Signup and view all the answers

    What is the primary function of a Cloud Chamber in radioactivity studies?

    <p>To provide detailed snapshots of particle paths</p> Signup and view all the answers

    Which device is specifically used to measure the rate of emission of α- or β-particles?

    <p>Geiger-Muller Counter</p> Signup and view all the answers

    What role does the scintillation counter serve in detecting radiation?

    <p>It produces electrical pulses in response to scintillations.</p> Signup and view all the answers

    What is one limitation of the film badge in detecting radiation?

    <p>It does not accurately measure ϒ-radiation intensity.</p> Signup and view all the answers

    What type of radiation does a film badge specifically track?

    <p>Both α- and β-particles.</p> Signup and view all the answers

    Which component in a modern scintillation counter replaces the zinc sulphide screen?

    <p>A crystal of sodium iodide with thallium iodide.</p> Signup and view all the answers

    How often should the film badge be developed to monitor radiation exposure?

    <p>Periodically based on exposure levels.</p> Signup and view all the answers

    What does the electrical pulse measured by a scintillation counter correspond to?

    <p>The number of scintillations detected.</p> Signup and view all the answers

    What is a key feature of radioactive decay according to Rutherford and Soddy's theory?

    <p>It involves the emission of α- or β-particles.</p> Signup and view all the answers

    What is the benefit of using a scintillation counter over a spinthariscope?

    <p>It can count a greater number of particles per second.</p> Signup and view all the answers

    What is the result of α-decay on the atomic mass of the parent nucleus?

    <p>Decreases by 4</p> Signup and view all the answers

    Which of the following correctly describes the process of β-decay?

    <p>A neutron converts into a proton and emits a β-particle.</p> Signup and view all the answers

    What is the relationship between the parent nucleus and the daughter nucleus after α-decay?

    <p>The daughter nucleus has a lower atomic mass and atomic number.</p> Signup and view all the answers

    If a parent nucleus has an atomic mass of 232 and undergoes 6 α-emissions, what will be its final atomic mass?

    <p>204</p> Signup and view all the answers

    What happens to the atomic mass of the nucleus during β-decay?

    <p>Remains unchanged</p> Signup and view all the answers

    Which of the following nuclei will have the same mass number but different atomic numbers after one β-emission?

    <p>Lead-214 and Bismuth-214</p> Signup and view all the answers

    What type of nucleus is formed when a radioactive element undergoes one α-emission and two β-emissions?

    <p>Isotopic nucleus</p> Signup and view all the answers

    What instrument is commonly used to determine the activity of a radioactive sample?

    <p>Geiger-Muller counter</p> Signup and view all the answers

    How can the half-life of an isotope be calculated?

    <p>By using the decay constant in a specific equation</p> Signup and view all the answers

    What is the rate of decay equal to in a radioactive sample?

    <p>The rate of emission of alpha particles</p> Signup and view all the answers

    What is the decay constant represented as mathematically in the equations?

    <p>λ</p> Signup and view all the answers

    If cobalt-60 has a half-life of 5.2 years, what can be inferred about its decay over time?

    <p>It will retain exactly half of its atoms after 5.2 years</p> Signup and view all the answers

    What is the activity of radon related to its mass in disintegrations per second?

    <p>It is equal to the number of atoms disintegrating per second</p> Signup and view all the answers

    Which of the following correctly describes the amount of sample left after a given time?

    <p>It can be calculated using the initial sample amount and the decay constant.</p> Signup and view all the answers

    What is the significance of the relationship between N0 and N in radioactive decay?

    <p>It indicates the fraction of the original sample remaining.</p> Signup and view all the answers

    What percentage of a cobalt-60 sample remains after 15 years if the disintegration constant is 0.13 yr^-1?

    <p>14%</p> Signup and view all the answers

    How long does it take for a sample of cobalt-60 to decay to only 2.0 percent of its original amount?

    <p>30 years</p> Signup and view all the answers

    What is the half-life of a radioactive isotope if it can decay from an initial amount to 1.25g after 40 days starting from 5g?

    <p>20 days</p> Signup and view all the answers

    How much time is required for a radioactive sample with a half-life of 33 minutes to lose one-third of its atoms?

    <p>19.31 minutes</p> Signup and view all the answers

    What is the remaining fraction N/N₀ of a radioactive isotope after one hour if its half-life is 47.2 seconds?

    <p>1.12 x 10^-23</p> Signup and view all the answers

    What is defined as the conversion of one element to another by a nuclear change?

    <p>Transmutation</p> Signup and view all the answers

    What is the primary outcome of a nuclear reaction?

    <p>Creation of a new atom with a different atomic number</p> Signup and view all the answers

    In the context of nuclear reactions, what does the term 'nuclear transmutation' refer to?

    <p>Artificial changes to atomic nuclei</p> Signup and view all the answers

    Study Notes

    Radioactivity (Lecture 2)

    • A nuclear reaction differs from a chemical reaction as it involves changes in the atom's nucleus, whereas a chemical reaction involves rearranging extra-nuclear electrons.
    • Nuclear chemistry studies changes in the nucleus of atoms, altering proton or neutron numbers, thereby forming new elements.
    • Some elements, like uranium and radium, are unstable. Their nuclei spontaneously break down, releasing excess particles and energy, which is called radiation.
    • Radioactive disintegration or decay is the spontaneous breaking down of unstable atoms. This process releases radiation, which characterizes radioactive elements.

    Types of Radiations

    • Radioactive radiations are categorized into three types.
    • Rutherford sorted these radiations by passing them through electrically charged plates.
    • Alpha (α) rays are positively charged and deflected towards the negative plate.
    • Beta (β) rays are negatively charged and deflected towards the positive plate.
    • Gamma (γ) rays are uncharged and pass straight through the electric field.

    Properties of Alpha, Beta, and Gamma Rays

    • Alpha (α), beta (β), and gamma (γ) rays exhibit different properties.
      • Velocity: Alpha particles are the slowest; beta particles are faster than alpha particles; gamma rays travel at the speed of light.
      • Penetrating power: Gamma rays are highly penetrating; beta particles have moderate penetration; alpha particles have the lowest penetrating power.
      • Ionisation: Alpha particles cause the most ionization; beta particles cause less ionization than alpha particles; gamma rays have the least ionization.

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    Radioactivity (Lecture 2) PDF

    Description

    This quiz covers Lecture 2 on Radioactivity, focusing on the differences between nuclear and chemical reactions, the study of nuclear chemistry, and the types of radioactive radiations. It explores radioactive decay and the characteristics of unstable elements. Test your understanding of these fundamental concepts of radioactivity!

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