State the full electronic configuration of $\text{Fe}^{2+}$.
Calculate the oxidation number of sulfur in the $\text{S}_2^{2-}$ ion. Assume that both sulfur atoms in the ion have the same oxidation number.
Describe the metallic bonding present in gold.
The sulfur dioxide made during roasting would lead to environmental effects if it escaped into the atmosphere. State and explain one of these environmental effects.
Finish the equation to represent the roasting of iron pyrite in oxygen.\n\n$4\text{FeS}_2 + \ldots \rightarrow 2\text{Fe}_2\text{O}_3 + \ldots$
An impure iron pyrite sample was roasted in oxygen. The composition of the solid products mixture is shown. Calculate the mass of $\text{FeS}_2$ present in the impure iron pyrite sample. Assume that every bit of the $\text{FeS}_2$ was changed into $\text{Fe}_2\text{O}_3$ during roasting.\n\n$(M_r:\ \text{FeS}_2,\ 120.0;\ \text{Fe}_2\text{O}_3,\ 159.6)$
Use your answer to c(iii) to work out the percentage by mass of gold in this sample of impure iron pyrite. Assume that gold is the only impurity in this sample of impure iron pyrite. Give your answer to two significant figures.