Compute the density of totally crystalline polyethylene, assuming that the equivalent of two ethylene repeat units is contained within each unit cell. a)- 99.8 g/cm3 b)- 0.998 g/cm3 c)- 0.499 g/cm3 d)- 49.9/cm3

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.