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

Covalent solutes separate into individual molecules when dissolved.
Covalent solutes separate into what when dissolved?

Deep currents are caused by differences in density at the top and bottom of the ocean.
What is caused by differences in density at the top and bottom of the ocean?

Allele frequecy is the rate at which a specific allele appears within a population.
What is the rate at which a specific allele appears within a population called?