Assume that Sodium is a monovalent free-electron metal and has a body-centric cubic structure. (i) Answer in ev. If the cubic cell side of sodium is 0. 4225 um, calculate its Fermi energy. (ii ) calculate the electrical resistivity of sodium at room temperature (assume a mean- free electron path equal to the inter-atomic separation ) and tell why this does not explain the measured conductivity . ( iii ) If the actual resistivity of a sample of sodium at room temperature is 5x1012 cm , estimate its expected thermal conductivity, stating any assumptions you are making