He is an expert in chemistry.

He received the letter challenging him to a duel and began preparing for the duel.

Gender roles are an important element in defining individual behavior in society.

His role is to fulfill his responsibilities as a leader.

Organic solvents play an important role in chemical reactions.

It is important to understand the importance of health.

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.