Question

when a high - mass main sequence star runs out of both hydrogen and helium in its core, the core begins to fuse . when nuclear fusion ends in a high - mass star, the heavy elements formed in the star’s core are released through a .

Explanation:

First blank (When a high - mass main sequence star runs out of both hydrogen and helium in its core, the core begins to fuse)

High - mass main sequence stars, after exhausting hydrogen and helium in their cores, start fusing heavier elements like carbon, oxygen, and then even heavier elements (up to iron in some cases) due to the high temperature and pressure in the core. The next available elements for fusion (after H and He) are heavier elements, typically starting with carbon and oxygen, and then proceeding to fuse elements like neon, magnesium, silicon, etc., until iron is formed (since fusion beyond iron does not release energy).

When nuclear fusion ends in a high - mass star (when it can no longer fuse elements to release energy, usually after forming iron in the core), the star undergoes a catastrophic collapse followed by a violent explosion known as a supernova. During a supernova explosion, the heavy elements that were formed in the star's core (elements heavier than iron are also formed in the supernova process) are released into space.

Answer:

heavier elements (e.g., carbon, oxygen, and then progressively heavier elements up to iron)

Second blank (When nuclear fusion ends in a high - mass star, the heavy elements formed in the star’s core are released through a)