Thorium is an element that occurs naturally in the earth's crust. The only naturally occurring isotope of thorium is 232Th and it is unstable and radioactive. The first step in the Thorium decay chain is the emission of an alpha particle. Which of these nuclei emerges from the decay?

A) 22888Ra

B) 23086Rn

C) 23289Ac

D) 23892U

Question

Chemistry

Walker

25 July, 07:29

Thorium is an element that occurs naturally in the earth's crust. The only naturally occurring isotope of thorium is 232Th and it is unstable and radioactive. The first step in the Thorium decay chain is the emission of an alpha particle. Which of these nuclei emerges from the decay?

A) 22888Ra

B) 23086Rn

C) 23289Ac

D) 23892U

+1

Answers (1)

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Reilly Powell · Answer 1

A, radium-228. Alpha radiation is essentially just two protons and two neutrons leaving the atom, causing the atomic number to drop by two (since the protons left) and the mass number to drop by four (since two neutrons and protons left).