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?

Q7:

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

  • A 𝑝 = 3 , 𝑞 = 1
  • B 𝑝 = 4 , 𝑞 = 1
  • C 𝑝 = 5 , 𝑞 = 2
  • D 𝑝 = 3 , 𝑞 = 2
  • E 𝑝 = 4 , 𝑞 = 2

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:

Element Radon Francium Radium Actinium Thorium Protactinium Uranium
Number of Protons 86 87 88 89 90 91 92

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?

  • A 𝛽
  • B 𝑎
  • C 𝛼
  • D 𝑒
  • E 𝑜

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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