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

Certain air pollutants form acid liquid when dissolved in water droplets in the air.
Certain air pollutants form which liquid when dissolved in water droplets in the air?

Phototaxis is the term for movement toward light.
What is the term for movement toward light?

Birds live and breed on seven of the continents.
On how many of the continents do birds live and breed?