31. Sulfur dioxide is extremely toxic and non-flammable.
A. True
B. False
32. The transfer of heat from one body to another takes place only when there is a temperature difference between the bodies.
A. Yes
B. No
33. A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as
34. Thermal diffusivity of a substance is given by (where h = Thermal diffusivity, ρ = Density of substance, S = Specific heat, and k = Thermal conductivity)
35. Which of the following statement is correct for ammonia as a refrigerant?
A. It is toxic to mucous membranes.
B. it requires large displacement per TR compared to fluoro carbons.
C. It reacts with copper and its alloys.
D. all of these
36. The wet bulb temperature at 100% relative humidity is __________ dew point temperature.
A. same as
B. lower than
C. higher than
37. The use of heat exchangers is made in
A. radiators in automobile
B. condensers and boilers in steam plants
C. condensers and evaporators in refrigeration and air conditioning units
D. all of the above
38. In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in
A. parallel flow
B. counter flow
C. cross flow
D. all of these
39. Which of the following statement is correct?
A. A grey body is one which absorbs all radiations incident on it.
B. At thermal equilibrium, the emissivity and absorptivity are same.
C. The energy absorbed by a body to the total energy falling on it is called emissivity.
D. A perfect body is one which is black in color
40. The horizontal and uniformly spaced lines on a psychrometric chart indicates relative humidity.
A. Correct
B. Incorrect