A physicist.
florist
A historian studies history.
Someone who studies dialects would usually be referred to as a "Linguist." Depending upon what their studies revolve around, you might hear them called a "Sociolinguist".
An egyptologist is someone who studies Egypt.
Geography and social studies
A person who studies islands is known as an island geographer or an insular researcher. They specialize in the study of islands' physical features, ecosystems, cultures, and geography.
You call someone that studies metal a metallurgist.
A physicist.
a person who studies planets is a planetologist.
There is no special name for someone who studies Hebrew.
A numismatist.
A Zoologist
An Anthropologist.
malacologist
euclidist
Gemologists