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

Collision theory states that chemical reactions occur when atoms, ions, or molecules collide.
What states that chemical reactions occur when atoms, ions, or molecules collide?

Tight junction is the term for a watertight seal between two adjacent animal cells.
What is the term for a watertight seal between two adjacent animal cells?

Phase is the term for a certain form of matter that has the same physical properties throughout.
What is the term for a certain form of matter that has the same physical properties throughout?