The structure of the stage-1 K_xC intercalate has been reported in space group Fddd with a pseudohexagonal unit cell of a = 4.92 Å, b = 8.51 Å, c = 21.4 Å with K at 0 0 0, C1 at 1 /4 1 /12 1 /8, C2 at 1 /4 1 /12 5 /8. With the assistance of a structure-drawing program:

(a) Sketch the structure of a single layer and annotate a simple 2D unit cell.

(b) Comment on the stacking sequence of layers relative to graphite.

(c) State the value of x in K_xC and comment on the value given that bcc K has a = 5.21 Å.

(d) Comment on the fact that Rb (Rb metal bcc a = 5.63 Å) and Cs (a = 6.06 Å) intercalates have similar structures.