For each of the following pairs of materials, decide which

For each of the following pairs of materials, decide which has the larger thermal conductivity. Justify your choices.
(a) Pure copper; aluminum bronze (95 wt% Cu-5 wt% Al).
(b) Fused silica; quartz.
(c) Linear polyethylene; branched polyethylene.
(d) Random poly(styrene-butadiene) copolymer; alternating poly(styrene-butadiene) copolymer.