What is the element at which the thermonuclear fusion chain definitively halts in the core of a massive star?

Answer

Iron (Fe)

The fusion chain stops definitively at iron because iron is the most stable atomic nucleus, meaning that fusing it consumes energy rather than releasing the necessary pressure-generating energy.

What is the element at which the thermonuclear fusion chain definitively halts in the core of a massive star?
evolutionstarsupernovaastrophysicsmass