Worksheet: Alpha Decay

In this worksheet, we will practice solving nuclear equations involving alpha decay.

Q1:

The following nuclear equation shows how an isotope of Neptunium decays to Protactinium: 237939142NpPa+𝛼. What is the value of 𝑚 in the equation?

Q2:

How many neutrons does an alpha particle have?

Q3:

How many protons does an alpha particle have?

Q4:

When a nucleus emits an alpha particle, by how much does the atomic number of the remaining nucleus decrease?

Q5:

When a nucleus emits an alpha particle, by how much does the mass number of the remaining nucleus decrease?

Q6:

What is the relative charge of an alpha particle?

  • A2
  • B1
  • C0
  • D1
  • E+2

Q7:

The following nuclear equation shows how an isotope of curium decays to plutonium via alpha decay. 2479624394CmPu+𝛼 What are the values of 𝑝 and 𝑞 in the equation?

  • A𝑝=3, 𝑞=2
  • B𝑝=4, 𝑞=2
  • C𝑝=3, 𝑞=1
  • D𝑝=5, 𝑞=2
  • E𝑝=4, 𝑞=1

Q8:

The following nuclear equation shows how an isotope of uranium decays to thorium: 2359223142UTh+𝛼. What is the value of 𝑛 in the equation?

Q9:

Which of the following statements correctly describes the process of alpha decay?

  • AIf a heavy unstable nucleus has too many protons, a proton may decay into a neutron, releasing a high-energy electron from the nucleus.
  • BIf a heavy unstable nucleus has too many nucleons, 2 protons may be ejected from the nucleus.
  • CIf a heavy unstable nucleus has too many nucleons, 2 protons and 2 neutrons may be ejected from the nucleus.
  • DIf a heavy unstable nucleus has too many neutrons, a neutron may decay into a proton, releasing a high-energy electron from the nucleus.
  • EIf an unstable nucleus has too many neutrons, one or more neutrons will be ejected from the nucleus.

Q10:

ElementRadonFranciumRadiumActiniumThoriumProtactiniumUranium
Number of Protons86878889909192

Thorium can undergo alpha decay. Which of the elements listed in the table does a thorium nucleus become when it undergoes alpha decay?

  • ARadon
  • BFrancium
  • CUranium
  • DActinium
  • ERadium

Q11:

Which of the following is the correct symbol for an alpha particle?

  • A𝛽
  • B𝑎
  • C𝛼
  • D𝑒
  • E𝑜

Q12:

The graph shows an isotope of uranium undergoing alpha decay. The number of protons of the isotope is shown on the 𝑥-axis, and the number of neutrons of the isotope is shown on the 𝑦-axis.

Which isotope of uranium does the graph show?

  • AUranium-235
  • BUranium-232
  • CUranium-233
  • DUranium-230
  • EUranium-234

Which isotope does the uranium become?

  • AThorium-232
  • BThorium-229
  • CThorium-230
  • DThorium-234
  • EThorium-224

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