The sourness of this lemon is very strong.

He is majoring in chemistry at university.

Carboxylic acids play a very important role in organic chemistry.

He is an expert in chemistry.

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

This lemon is sour.

Please add a little vinegar to this salad.

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.