Find the mass of water vapour per cubic metre of air at temperature 300K and rekative humidity 50%. The saturation vapour pressure at 300K is 3.6kPa and the gas constant `R=8.3JK^(-1)mol^(-1)`.

Explanation

To find the mass of water vapor per cubic meter of air at a temperature of 300K and a relative humidity of 50%, we can follow these steps:

### Step 1: Understand the given data
- Temperature (T) = 300 K
- Relative Humidity (RH) = 50% = 0.5
- Saturation Vapor Pressure (P_s) at 300 K = 3.6 kPa = 3600 Pa (since 1 kPa = 1000 Pa)
- Gas constant (R) = 8.3 J/(K·mol)
- Molecular weight of water (H2O) = 18 g/mol = 0.018 kg/mol (converting grams to kilograms for consistency)
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