In comparison to eukaryotes, prokaryotes -Are smaller and lack a nucleus-
The correct answer is Chemical. Because two substances are reacting and creating a new substance.
It indicates what elements is composed by and how many atoms of one element are linked to the other.
For example, this is the formula for table salt is:
NaCl
The formula indicates that table salt (sodium chloride) is composed by sodium (Na) and chlorine (Cl) on a 1:1 ratio.
Hope it helped,
BioTeacher101