(a) Describe the solid state structures of K₃C₆₀ and of KC₈. Comment on any physical or chemical properties of the compounds that are of interest.

(b) Comment on the use of lead(II) acetate in a qualitative test for H₂S.

(c) In the [Et₄N]⁻ salt, the [C₂S₄]²⁻ ion is nonplanar; the dihedral angle between the planes containing the two CS₂ groups is 908. In contrast, in many of its salts, the [C₂O₄]²⁻ ion is planar. Deduce, with reasoning, the point groups of these anions.