T(oC) 0 5 10 15 20 40 60 S.V.P (mmHg) 4.58 6.51 8.94 12.67 17.50 55.10 149.00 The table above shows the saturation vapour pressure against temperature in a ...

Answer Details

To find the relative humidity, we need to first calculate the actual vapour pressure (e) at 20°C using the table. We know that the saturation vapour pressure (e_s) at 20°C is 10 mmHg, but we need to determine the actual vapour pressure to calculate the relative humidity. From the table, we can see that the saturation vapour pressure at 20°C is 17.50 mmHg. Since the actual vapour pressure is given as 10 mmHg, we can calculate the relative humidity using the following formula: Relative humidity = (actual vapour pressure/saturation vapour pressure) × 100% Relative humidity = (10/17.50) × 100% Relative humidity = 57.1% Therefore, the relative humidity in this town at 20°C is approximately 57.1%. So, option B (57.0%) is the correct answer.