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Difficulty: EasyNatural Radioactivity and Radiation Emissions

Which of the following natural radioactive emissions has the least penetrating power and can be stopped by a thin sheet of paper?

  1. Alpha particlesAnswer
  2. B
    Beta particles
  3. C
    Gamma rays
  4. D
    Neutrons

Answer

Alpha particles have the lowest penetrating power of the three primary natural radioactive emissions and are stopped by a thin sheet of paper.
Alpha particles consist of heavy, doubly charged helium nuclei (24He^4_2\text{He}). Their relatively large size and strong positive charge lead to frequent ionizing collisions with surrounding atoms, causing them to deposit their energy over a very short distance and making them unable to pass through a simple sheet of paper.

Step-by-Step Solution

1
Identify the nature and physical properties of natural radioactive emissions (alpha particles, beta particles, and gamma rays).
Alpha particles consist of 2 protons and 2 neutrons (helium nucleus, 24He^4_2\text{He}), carrying a heavy mass (4 u4\text{ u}) and a +2e+2e charge.
Large mass and high charge increase the likelihood of collisions with atoms in matter.
2
Compare ionizing ability and penetrating power across emission types.
Because alpha particles cause high ionization over short distances, they lose kinetic energy rapidly.
High rate of energy loss corresponds directly to very low penetrating depth.
3
Determine the stopping material required for alpha particles.
Alpha particles are absorbed by a thin layer of matter, such as a single sheet of paper or a few centimeters of air.
This confirms alpha radiation has the least penetrating power among natural emissions.

Key Concept

Relative Penetrating and Ionizing Capacities of Natural Radioactive Emissions
Estimated Time:45s
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Topics

Natural Radioactivity and Radiation Emissions

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