Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Compounds containing an atom of nitrogen element, bonded in a hydrocarbon framework, are classified as amines.
Compounds containing an atom of what element, bonded in a hydrocarbon framework, are classified as amines?

Digestion begins in the gastrovascular cavity.
Where does digestion begin?

The core of a star collapses during a supernova, forming a neutron star.

The core of a star collapses during what event, forming a neutron star?