Did anyone else struggle with the conductance question? I think it was question 4, where we there was a 4x20 array of atoms. I took the length to be 20 * 0.38E-9 and the width to be 4 * 0.38E-9.
As G = σA / L, am I right in assuming that G = σ * width ? Using this, I got a conductance of about 5E-5 S, which was not the 25E-6 S it asked for. I can't remember the value of the conductivity in the question, but perhaps it was wrong?