The vapor pressure of water at 10 °C is 1300 Pa. (a) what percentage of atmospheric pressure is this? Take atmospheric pressure to be 1.013 × 105Pa. (b) what percentage of the total air pressure at 10 °C is due to water vapor when the relative humidity is100%? (c) The vapor pressure of water at 20 °C is 2500 Pa. What is the relative humidity at this temperature if the partial pressure of water in the air has not changed from what it was at 10 °C when the relative humidity was 100%?