Question

Which of the following ionic compounds are named correctly ?

1.) Cr₂O₃ - chromium III oxide
2.) CuSO₄ - copper II sulfate
3.) PbO₂ - lead II oxide
4.) SnF₂ - tin III fluroide
5.) NiCO₃ - nickel IV carbonate

Answer 1

The compound PbO₂ is correctly named lead (IV) oxide, and NiCO₃ is correctly named nickel (II) carbonate, based on the charges of the ions present in each compound.

Step-by-step explanation:

The question pertains to the correct naming of ionic compounds, particularly those containing metals that can have multiple oxidation states. The correct names are determined by the charge of the ions that make up the compound. For compounds of lead and nickel that can have more than one oxidation state, the charge is indicated by a Roman numeral in parentheses after the metal name.

Regarding the two compounds you have inquired about, PbO₂ is named lead (IV) oxide, not lead (II) oxide, because lead is in the +4 oxidation state here, as each oxygen atom has a 2- charge and there are two of them. So the lead must balance this with a +4 charge.

For NiCO₃, the compound is correctly named nickel (II) carbonate. This is because carbonate (CO₃) has a 2- charge, and since there is only one nickel ion needed to neutralize the charge, it implies the nickel ion has a +2 charge.