This question comes with these answer choices:
a) K₃N (potassium nitride)
b) TiO₂ (titanium(II) oxide)
c) SnBr₄ (tin(IV) bromide)
d) PBr₅ (phosphorus pentabromide)
e) CaS (calcium sulfide)
Answer: option b) TiO₂ (titanium(II) oxide)
Justification:
a) K₃N (potassium nitride)
K⁺¹ is the correct ion (cation) of potassium: oxidation state 1+.
N⁻³ is the correct anion of nitrogen: oxidation state 3⁻.
According to accepted IUPAC nomenclature rules, the name of the anion is nitride, so the name potassium nitride is correct.
b) TiO₂ (titanium(II) oxide)
When you calcualte the oxidation state of Ti, it is 4+, since (4+) + 2(2-) = 4 - 4 = 0.
So, the oxidation number of titanium is 4, and the correct name of the compound is titanium(IV) oxide.
The name titanium(II) oxide indicates that the oxidation state of Ti is 2, which is not true.
c) SnBr₄ (tin(IV) bromide)
It is correct because the oxidation state of Sn is 4+.
d) PBr₅ (phosphorus pentabromide)
It is correct because they are using the (accepted) systematic nomenclature in which the prefix is used to indicate the number of atoms in the formula.
Penta means 5, so penta bromide indicates 5 atoms of bromine.
e) CaS (calcium sulfide)
It is correct using the systematic nomenclature, because there is one atom of Ca and one atom of S.
