For each of the following pairs of materials, decide which has the larger thermal conductivity. justify your choices. (a) pure silver; sterling silver (92.5 wt% ag–7.5 wt% cu) (b) fused silica; polycrystalline silica (c) linear and syndiotactic poly(vinyl chloride) (dp = 1000); linear and syndiotactic polystyrene (dp = 1000) (d) atactic polypropylene (mw = 106 g mol); isotactic polypropylene (mw = 105 g mol)