This lemon is sour.

Please add a little vinegar to this salad.

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.

Yoshisawa went out by car.

This reaction occurs through a chemical process.

He is an excellent chemist who made many discoveries.