Q. A sphere 15 cm in diameter is covered with 5 cm of insulation (k = 0.057 kcal/m-hr-?C). The inside and outside surface temperature of the insulation are 315?C and 80?C respectively. The heat loss per sq. m of the outside surface will be closer to

• (A) 80 kcal/hr
• (B) 320 kcal/hr
• (C) 160 kcal/hr
• (D) 37,500 kg