Physics is a difficult subject.

This is my precious thing.

He created a new story.

That's a new thing, isn't it?

He is dedicated to the study of immunochemistry.

Thermochemistry is a part of chemistry that deals with the reactions of heat and matter.

This chemical reaction is very dangerous.

This shirt is made of chemical fiber.

The use of chemical weapons is prohibited by international law.

I am majoring in biochemistry at university.