My grandfather is being seen by a specialist in geriatric medicine.

I am majoring in biology at university.

He proposed a new theory about quantum mechanics.

He is an expert in petrochemistry.

He is an expert in folklore studies, and his research is highly regarded worldwide.

The concept of chemical equivalent is essential for understanding chemical reactions.

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.

He decided to suspend his studies for health reasons.