Which element is the heaviest (has the highest atomic number) that can be formed by fusion in the core of massive stars before supernova?

• A. Nickel (Ni)
• B. Uranium (U)
• C. Gold (Au)
• D. Iron (Fe)

Answer: (D)

Verified step by step guidance

1. Understand that in the cores of massive stars, elements are formed by nuclear fusion, where lighter nuclei combine to form heavier nuclei, releasing energy up to a certain point.
2. Recall that fusion processes in stars proceed up to the formation of elements around iron (Fe) on the periodic table because iron has the highest binding energy per nucleon, making further fusion energetically unfavorable.
3. Recognize that elements heavier than iron, such as nickel (Ni), uranium (U), and gold (Au), are not typically formed by fusion in stellar cores but rather by other processes like neutron capture during supernova explosions.
4. Identify that among the options given, iron (Fe) is the heaviest element that can be formed by fusion in the core of massive stars before a supernova occurs.
5. Conclude that the fusion process in massive stars stops at iron because fusing elements heavier than iron requires energy input rather than releasing energy, which is why iron is the endpoint of fusion in stellar cores.