instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
If a substance has a ph value greater than 7,that indicates that it is base.
answer:
If a substance has a ph value greater than 7, what does it indicate?


question:
If an air mass forms over an ocean it is called a maritime air mass.
answer:
If an air mass forms over an ocean it is called what type of air mass?


question:
Gases is less dense then either solids or liquids.
answer:
What is less dense then either solids or liquids?