Question

The liquid oxygen having the boiling point temperature of -183°C is to be stored in spherical container of 30cm diameter. The system is insulated by an evacuated space between the inner sphere and surrounding 45cm in diameter concentric sphere. For the outer surface of inner sphere and inner surface of outer sphere the emmisssivity is 0.03 and temperature of inner surface of outer sphere is 30°C. Neglecting the thickness of inner and outer spheres.

If the latent heat of vaporization of oxygen is 315 KJ/kg, the amount of oxygen evaporation per day is

• A. 46.27 kg/day
• B. 0.77 kg/day
• C. 0.462 kg/day
• D. 23.14 kg/day

Answer 1

The correct option is B 0.77 kg/day

The amount of oxygen evaporated per day

$m=\frac{\text{Heat enters in to the inner sphere in a day}}{\text{latent heat of vapourisation}}$

$=\frac{2.81\times 60\times 60\times 24}{315\times {10}^3}=0.77kg/day$