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

Plasma matter makes up most of the universe.
What type of matter makes up most of the universe?

A bow wake is created when the wave source moves faster than the wave propagation speed.
What is created when the wave source moves faster than the wave propagation speed?

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?