Worksheet: Decay Chains

In this worksheet, we will practice describing the four radioactive decay chains and identifying the decay chain of an isotope from its nuclide symbol.

Q1:

An atom of 238U converts to 210Pb via a sequence of 11 nuclear decays. The second, third, ninth, and tenth decays are 𝛽 decays and the others are 𝛼 decays. Which of the following nuclides is not formed in this decay pathway?

  • A 2 1 8 A t
  • B 2 1 8 P o
  • C 2 1 4 B i
  • D 2 1 4 P o
  • E 2 1 4 P b

Q2:

An atom of 222Rn converts to 206Tl via a sequence of 7 nuclear decays. The second, fourth, and seventh decays are 𝛽 decays and the others are 𝛼 decays. Which of the following nuclides is not formed in this decay pathway?

  • A 2 1 8 A t
  • B 2 1 0 B i
  • C 2 1 4 P o
  • D 2 1 0 P b
  • E 2 0 6 H g

Q3:

An atom of 249Cf decays to 213Po via a series of 𝛼 and 𝛽 decays.

How many 𝛼 decays take place?

How many 𝛽 decays take place?

Q4:

An atom of 239Np decays to 207Pb via a series of 𝛼 and 𝛽 decays.

How many 𝛼 decays take place?

How many 𝛽 decays take place?

Q5:

An atom of 234Th decays to 206Pb via a series of 𝛼 and 𝛽 decays.

How many 𝛼 decays take place?

How many 𝛽 decays take place?

Q6:

An atom of 233U decays to 209Pb via a series of 𝛼 and 𝛽 decays.

How many 𝛼 decays take place?

How many 𝛽 decays take place?

Q7:

In which of the following groups do the listed nuclides form part of the same decay chain?

  • A 2 4 8 2 1 4 2 2 4 2 3 2 C m , P b , R a , T h
  • B 2 2 9 2 2 3 2 4 3 2 1 1 T h , F r , A m , B i
  • C 2 1 8 2 0 6 2 1 2 2 3 8 P o , H g , P b , U
  • D 2 4 3 2 1 5 2 3 1 2 3 5 P u , A t , P a , U
  • E 2 3 7 2 2 5 2 3 1 2 2 1 N p , A c , T h , F r

Q8:

Which of the following nuclei is likely to decay to 209Bi?

  • A 2 3 8 U
  • B 2 2 3 R a
  • C 2 4 4 P u
  • D 2 1 8 P o
  • E 2 3 3 P a

Q9:

Which of the following nuclei is likely to decay to 206Pb?

  • A 2 1 1 B i
  • B 2 4 0 U
  • C 2 2 4 R a
  • D 2 1 7 A t
  • E 2 1 8 P o

Q10:

Which of the following nuclei is likely to decay to 207Pb?

  • A 2 2 8 A c
  • B 2 2 5 R a
  • C 2 4 5 C f
  • D 2 2 7 T h
  • E 2 2 2 R n

Q11:

Which of the following nuclei is likely to decay to 208Pb?

  • A 2 2 7 A c
  • B 2 3 4 T h
  • C 2 2 8 R a
  • D 2 2 1 F r
  • E 2 1 8 A t

Q12:

An atom of 221Fr converts to 209Bi via a sequence of 5 nuclear decays. The fourth and fifth decays are 𝛽 decays and the others are 𝛼 decays. Which of the following nuclides is not formed in this decay pathway?

  • A 2 1 3 B i
  • B 2 1 3 P o
  • C 2 1 7 A t
  • D 2 0 9 P b
  • E 2 0 9 T l

Q13:

An atom of 231Pa converts to 211Bi via a sequence of 7 nuclear decays. The third and seventh decays are 𝛽 decays and the others are 𝛼 decays. Which of the following nuclides is not formed in this decay pathway?

  • A 2 2 3 F r
  • B 2 2 3 R a
  • C 2 2 7 T h
  • D 2 1 1 P b
  • E 2 1 9 R n

Q14:

An atom of 224Ra converts to 208Pb via a sequence of 6 nuclear decays. The fourth and fifth decays are 𝛽 decays and the others are 𝛼 decays. Which of the following nuclides is not formed in this decay pathway?

  • A 2 1 6 P o
  • B 2 1 2 B i
  • C 2 0 8 T l
  • D 2 1 2 P o
  • E 2 1 2 P b

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