He is an expert in chemistry.

There is a class observation at my son's school tomorrow.

Organic solvents play an important role in chemical reactions.

The use of mobile phones is prohibited during class.

She overreacted to his words.

Nuclear reactions are used for mass production of energy.

His single word triggered a chain reaction, and everything changed.

I was surprised by his overreaction.

His body showed a rejection reaction to the transplanted organ.

He is dedicated to the study of immunochemistry.