Respuesta :
There are 3 nomenclature types, so you have to be attentive of which one it is:
Hydrochloric acid: It is a hydracid, it is composed only of the elements present in the name (hydrogen and chloride).
[tex]HCl\text{ }\rightarrow\text{ The oxidation number of the halogen is always -1}[/tex]Copper (II) chloride: It's a salt composed of a metal and a halogen. The oxidation number of the halogen is -1 also in this case. This type of nomenclature tells us which is the oxidation number of the copper also, and it is the number between the parenthesis (+2).
[tex]Cu^{+2}Cl^-\text{ }\rightarrow\text{ CuCl}_2[/tex]Dinitrogen pentoxide: This type of nomenclature shows the number of atoms of each element present in the formula (di is 2, and penta is 5):
[tex]N_2O_5[/tex]Aluminum sulfide: In the sulfides, there's the element named plus sulfur (with an oxidation number of -2). The aluminum only has +3 in its oxidation number:
[tex]Al^{+3}S^{-2}\text{ }\rightarrow\text{ Al}_2S_3[/tex]Iron (II) nitride: In this case, the nitride means it's going to be nitrogen (with an oxidation number of -3) and the other element, in this case, iron (with an oxidation number of +2, as it says in the name):
[tex]Fe^{+2}N^{-3}\text{ }\rightarrow\text{ Fe}_3N_2[/tex]