Refrigeration and Air Conditioning
Relative humidity is given by (where pv = Partial pressure of water vapour, pb = Barometric pressure, ps = Pressure of saturated air, pd = Pressure at dry bulb temperature, pw = Saturation pressure corresponding to wet bulb temperature, and μ = Degree of saturation)

[Pv (Pb - Pd)]/ [Pd (Pb - Pv)]
0.622 Pv / (Pb - Pv)
μ/[1 - (1 - μ) (Ps/Pb)]
None of these

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Refrigeration and Air Conditioning
Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since

These react with ozone layer
These react with plants and cause greenhouse effect
These react with water vapour and cause acid rain
These react with oxygen and cause its depletion

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