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

Seedless and seed are the two divisions of vascular plants.
What are the two divisions of vascular plants?

Some compounds form rigid frameworks called crystals.
Some compounds form rigid frameworks called what?

The ph scale measures acids and bases and has 7 as a neutral value.
Which scale measures acids and bases and has 7 as a neutral value?