Question

1. when a star begins to produce ____, it will collapse under its own gravity to a neutron star or black hole. hydrogen iron helium carbon

Explanation:

Stars undergo nuclear fusion. Hydrogen fusion is a main - stage process. Helium and carbon are also products of fusion in stars. However, when iron is produced in a star's core, nuclear fusion of iron does not release energy (unlike lighter elements). This causes the star to no longer be able to support itself against gravitational collapse.

Answer:

iron