The humidity ratio of atmospheric air at 28 °C dry-bulb temperature and 760 mm of mercury is 0.016 kg/kg of dry air. Determine (1) the partial pressure of water vapour (bar), (2) the relative humidity, (3) the dew-point temperature and (4) the specific enthalpy (kJ/kg dry air). Saturation pressure at 28 °C = 0.03782 bar; use steam tables for the dew point.