A student doing a laboratory study on determination of molecular mass of gases obtained the following data for one of his unknowns: 6.155 grams of the gas occupied a volume of 1484 mL when its temperature was 81.14 °F and its pressure was 747.2 mmHg. Calculate the molecular mass of the gas, assuming ideal gas behavior. R = 8.314 J K-1 mol-1, R= 0.082 Latm mol-1 K-1, R = 1.987 Cal K-1 mol-1?