11. According to Dalton’s law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)
A. Pb = pa – pv
B. Pb = pa + pv
C. Pb = pa x pv
D. Pb = pa/pv
12. The heat transfer by conduction through a thick sphere is given by
13. The relative humidity is defined as
A. the mass of water vapor present in 1 m3 of dry air
B. the mass of water vapor present in 1 kg of dry air
C. the ratio of the actual mass of water vapor in a unit mass of dry air to the mass of water vapor in the same mass of dry air when it is saturated at the same temperature and pressure.
D. the ratio of actual mass of water vapor in a given volume of moist air to the mass of water vapor in the same volume of saturated air at the same temperature and pressure
14. Fourier’s law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)
15. The heat transfer by conduction through a thick sphere is same as through a thick cylinder.
A. True
B. False
16. In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively
A. water and water
B. water and lithium bromide
C. ammonia and lithium bromide
D. ammonia and water
17. As relative humidity decreases, the dew point temperature will be __________ wet bulb temperature.
A. same as
B. lower than
C. higher than
18. The process of heat transfer from a hot body to a cold body, in a straight line, without affecting the intervening medium, is called radiation.
A. True
B. False
19. Reynolds number (RN) is given by (where h = Film coefficient, l = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, ρ = Density of fluid, cp = Specific heat at constant pressure, and μ = Coefficient of absolute viscosity)
20. The optimum effective temperature for human comfort is
A. higher in winter than in summer
B. lower in winter than in summer
C. same in winter and summer
D. not dependent on season