He is majoring in chemistry at university.

This chemical reacts when heat is added.

This chemical reaction is very dangerous.

He is an expert in chemistry.

I can't drive the car because there is a shortage of gasoline.

The existence of dark matter has not yet been fully proven.

Antibiotics don't work for colds, so please don't take them unnecessarily.

It is said that antimatter has properties opposite to those of matter.

This food may contain carcinogens.

The air in this area is greatly affected by pollutants emitted from factories.