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

Antifreeze lowers it the freezing temperature of the water in car radiators.
What does antifreeze do to the freezing temperature of the water in car radiators?

Sodium-potassium pumps help nerve cells establish a voltage across their plasma membranes.
Sodium-potassium pumps help nerve cells establish a voltage across their what?

Pure chemical substance type of substance is any matter that has a fixed chemical composition and characteristic properties.

What type of substance is any matter that has a fixed chemical composition and characteristic properties?