He is an expert in petrochemistry.

It's difficult to decipher this chemical equation.

Understanding chemical equations is difficult.

He is an expert in chemical analysis.

We are growing vegetables without using chemical fertilizers.

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

Understanding chemical equilibrium is very important in understanding chemical reactions.

In this experiment, you can observe a chemical reaction.

This substance undergoes a chemical change when heat is applied.

The use of chemical weapons is prohibited by international law.