(a) Draw the structure of P₄S₃ and describe an appropriate bonding scheme for this molecule. Compare the structures of P₄S₁₀, P₄S₃ and P₄, and comment on the formal oxidation states of the P atoms in these species.

(b) The electrical resistivity of Bi at 273K is 1:07 × 10⁻⁶Ωm. How do you expect this property to change as the temperature increases? On what grounds have you drawn your conclusion?

(c) Hydrated iron(III) nitrate was dissolved in hot HNO₃ (100%), and the solution was placed in a desiccator with P₂O₅ until the sample had become a solid residue. The pure Fe(III) product (an ionic salt [NO₂][X]) was collected by sublimation; crystals were extremely deliquescent. Suggest an identity for the product, clearly stating the charges on the ions. The Fe(III) centre has a coordination number of 8. Suggest how this is achieved.