Question

in a radioactive decay series, th-232 decays to ra-228. which type of decay is being represented?

○ gamma radiation

○ alpha radiation

○ beta radiation

question 3
1 pts
an element that has a mass number less than 60 is a fissionable element

Explanation:

For the first question (decay type):

1. Recall decay types:

• Alpha decay: Emits a helium nucleus ($\ce{^4_2He}$), so mass number decreases by 4, atomic number by 2.
• Beta decay: Emits an electron ($\ce{^0_{-1}e}$), mass number unchanged, atomic number increases by 1.
• Gamma decay: No change in mass/atomic number (energy release).

1. Analyze Th-232 (Th: atomic number 90, mass 232) to Ra-228 (Ra: atomic number 88, mass 228):

• Mass number change: \( 232 - 228 = 4 \).
• Atomic number change: \( 90 - 88 = 2 \).

1. Match to decay: This matches alpha decay (mass -4, atomic -2). Gamma and beta do not fit.

Fission involves splitting heavy nuclei. Light elements (mass < 60) lack sufficient nucleons for fission; they are fusion - prone. Thus, the statement is incorrect.

Answer:

B. Alpha radiation

For the second question (fissionable element):

(Note: The statement is false. Fissionable elements typically have high mass numbers (e.g., U-235, Pu-239), while light elements (mass < 60) are more likely to undergo fusion, not fission.)