Hydrogen sulphide is extremely toxic, and particularly at high concentrations, it is lethal to humans.

This compound is stabilized by hydrogenation.

He hydrogenated fatty acids in a chemical experiment.

This reaction occurs through a chemical process.

He is an excellent chemist who made many discoveries.

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.