I found an old box in the storeroom.

He has a special ability.

This reaction occurs through a chemical process.

He is an excellent chemist who made many discoveries.

He is an expert in petrochemistry.

He is an expert in chemical analysis.

It's difficult to decipher this chemical equation.

Understanding chemical equations is difficult.

We are growing vegetables without using chemical fertilizers.

Oxygen, which is one of the chemical elements, is necessary for us to breathe.