Geology is the science of Earth.
Ecology is the science of relationship between an organism and its environment.
Astronomy is the science of studying astronomical objects.
Whereas, Phrenology is the study of relating the size of human skull like its size, shapes e.t.c to his/her personality. So, its not a science as there is no scientific relationship between it.
You may tell when a solution os formed when the item or particle, such as sugar or salt,
dissolves completely in the solvent, such as water.
Basically, you know when a solution is formed when the material you have placed in the solvent disappears :P
I have provided the steps to figure out the number of atoms in the chemical compound.