Question

what other elements does a star burn as fuel besides hydrogen?

Answer 1

At conditions hot enough for fusion molecules don't exist, you get individual atoms instead. So water and carbon monoxide would fall apart to hydrogen, carbon and oxygen.

Stars which don't contain enough hydrogen to start fusion would probably never ignite (remaining a brown dwarf) or collapse directly to a neutron star (if the star is massive enough to overcome electron degeneracy). The heavier elements can fuse together, but this requires very high temperatures. You are unlikely to achieve such temperatures if you don't start with hydrogen fusion. As far as we know all stars contain large amounts of hydrogen (simply because it the most common element in the universe), so this is purely hypothetical.

YOU CAN FIND IT HELPFUL...

The most common elements, like carbon and nitrogen, are created in the cores of most stars, fused from lighter elements like hydrogen and helium. The heaviest elements, like iron, however, are only formed in the massive stars which end their lives in supernova explosions. Still other elements are born in the extreme conditions of the explosion itself. Without supernovae, life would not be possible. Our blood has iron in the hemoglobin which is vital to our ability to breath. We need oxygen in our atmosphere to breathe. Nitrogen enriches our planet's soil. Earth itself would be a very different place without the elements created in stars and supernova explosions.