Refrigeration and Air Conditioning
The leaks in a refrigeration system using Freon are detected by

Halide torch which on detection produces greenish flame lighting
Sulphur sticks which on detection gives white smoke
Smelling
Using reagents

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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)

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

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