TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Elements are pure substances that make up all matter.

SOLUTION: Elements are pure substances that make up what?

PROBLEM: Stem basic plant structure facilitates dispersal of pollen and fruit by raising reproductive structures.

SOLUTION: What basic plant structure facilitates dispersal of pollen and fruit by raising reproductive structures?

PROBLEM: Hydrogen gas is generated by the reaction of nitric acid and elemental iron else.

SOLUTION:
Hydrogen gas is generated by the reaction of nitric acid and what else?