This substance undergoes a chemical change when heat is applied.

In this experiment, you can observe a chemical reaction.

Understanding chemical equilibrium is very important in understanding chemical reactions.

He is an excellent chemist who made many discoveries.

This reaction occurs through a chemical process.

He is an expert in petrochemistry.

According to the law on specified alien species, the import of certain organisms is prohibited.

He is suffering from combat stress reaction.

The doctor said that his vision loss was due to a problem with the vitreous body.

The study of chromosomes is an important part of cytology.