1. At the top of a mine downcast shaft the barometric pressure is 100kpa and the air temperatura is 18 c. at the shaft bottom, the corresponding measurements are 110 kpa and 27.4c respectively. The airflow measured at the shaft top is 200 m3/s. if the shaft is dry, determine: a) The air densities at the shaft top and shaft bottomb) The mass flow of airc) The volumen flow of air at the shaft bottom

2. A) Air is supplied at a rate of 5m3/s to ten persons working at a moderate rate in a mine heading. The intake air contains 20.6 percent oxygen and 0.1 percent carbn dioxide. Determine the changes in concentrations of these gases caused by respiration. B) what is the (in ft or m ) of the column of dry air equivalent to a heat of 1 in(25.4 mm) wter? Asume standard conditions

3. An analysis of air samples taken in a return airway indicates the following gas concentrations: Carbn dioxide: 0.2 percent, carbn monoxide: 10 ppm Hydrogen sulphisde: 2 ppm, sulphur dioxide: 1 ppm Determine the threshold limit values, twa and STEL for the mixture.