The isotopes are all stable, while is radioactive. The mode of decay for is most likely to be
A) positron decay.
B) α decay.
C) decay.
D) electron capture.
E) β decay.

Question

The isotopes  are all stable, while  is radioactive. The mode of decay for  is most likely to be
A) positron decay. 
B) α decay. 
C) decay. 
D) electron capture. 
E) β decay.

Quizplus · Accepted Answer

The fact that one of the isotopes is radioactive implies that it undergoes decay. The most common types of radioactive decay are α decay, β decay, and γ decay. Positron decay and electron capture are both specific types of β decay. Given that the isotope in question is unstable, α decay can be immediately ruled out as it only occurs for highly unstable isotopes. Additionally, there is no mention of gamma rays in the question stem, so γ decay can be ruled out as well. Therefore, the most likely mode of decay for this isotope is β decay, which includes both positron decay and electron capture. However, given that the question asks for the "most likely" mode, the correct choice is E - β decay - as β decay is much more common than positron decay or electron capture.

The Isotopes Are All Stable, While Is Radioactive