A copper ball of 20 cm diameter is kept outside open to sky during summer. The ball is capable of receiving and emitting heat by radiation. Identify the satisfactory conditions from the following to treat the ball as a block body. the emissivity and absorptivity of the ball should be equal to onell) the reflectivity and transmissivity of the ball should be equal to onelll) the ball should emit lesser the heat absorbed O a. I and Il only O b. I, II and III O c. I only O d. ll only O e. Il and Ill only On a hot sunny day, one of the walls of a building receives heat due to solar radiation incident of 150 W/m2. So that the temperature of inner and outer surface of the wall is at 15°C and 34°C respectively. The ambient air outside the building is at 20°C. The ambient air side convective heat transfer coefficient can be computed using O a. Inverse square law of radiation O b. Stefan-Boltzmann law O c Newton's law of cooling O d. Kirchhoff's law of radiation