21. The wet bulb temperature lines, on the psychrometric chart, are curved lines.

A. True
B. False

22. The sensible heat factor during cooling and dehumidification process is given by (where h₁ = Enthalpy of air entering the cooling coil, h₂ = Enthalpy of air leaving the cooling coil, and h_A = Enthalpy of air at the end of dehumidification process)

23. Thermal diffusivity is a

A. function of temperature
B. physical property of a substance
C. dimensionless parameter
D. all of these

24. The condition of refrigerant after leaving the compressor and before entering the condenser is superheated vapor.

A. Yes
B. No

25. The total radiation from a black body per second per unit area is __________ fourth power of the absolute temperature. This statement is known as Stefan-Boltzmann law.

A. equal to
B. directly proportional to
C. inversely proportional to

26. Which of the following represents a heat pump?

27. In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be

A. 0.3
B. 0.6
C. 0.67
D. 1.5

28. The amount of radiation mainly depends upon the

A. nature of the body
B. temperature of the body
C. type of surface of the body
D. all of these

29. For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of

A. copper
B. aluminum
C. steel
D. brass

30. The highest thermal diffusivity is of

A. iron
B. lead
C. concrete
D. wood