I am majoring in physical chemistry at university.

I love organic chemistry classes.

He is majoring in soil science at university.

I am majoring in social science at university.

He is majoring in logic at university.

He is an expert in topology.

He is an expert in crystallography.

Semiotics is the study of signs and symbols used in society and culture.

He is an expert in psychiatry.

This reaction has reached chemical equilibrium.