He is an expert in chemistry.

Organic solvents play an important role in chemical reactions.

The use of mobile phones is prohibited during class.

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

His body showed a rejection reaction to the transplanted organ.

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

She overreacted to his words.

Nuclear reactions are used for mass production of energy.

I was surprised by his overreaction.

This reaction occurs through a chemical process.