Which process is primarily responsible for the formation of elements heavier than iron in the universe?

• A. Radioactive decay of lighter elements
• B. Supernova nucleosynthesis during the explosion of massive stars
• C. Nuclear fusion in the cores of main-sequence stars
• D. Chemical reactions in interstellar clouds

Answer: (B)

Verified step by step guidance

1. Understand that elements heavier than iron require energy input to form because fusing elements beyond iron is endothermic, meaning it consumes energy rather than releases it.
2. Recall that nuclear fusion in the cores of main-sequence stars primarily produces elements up to iron, but not heavier elements, due to energy constraints.
3. Recognize that radioactive decay of lighter elements and chemical reactions in interstellar clouds do not create heavier elements; they involve transformations or rearrangements of existing atoms rather than forming new heavier nuclei.
4. Identify that supernova nucleosynthesis occurs during the explosive death of massive stars, providing the extreme temperatures and neutron flux necessary to create elements heavier than iron through rapid neutron capture processes (r-process).
5. Conclude that the primary process responsible for the formation of elements heavier than iron in the universe is supernova nucleosynthesis during the explosion of massive stars.