The envelope and basket of a hot-air balloon have a combined weight of 2.36 kN, and the envelope has a capacity (volume) of 2.11 x 103 m3. When it is fully inflated, what should be the temperature of the enclosed air to give the balloon a lifting capacity (force) of 2.52 kN (in addition to the balloon's weight)? Assume that the surrounding air, at 20.0 C, has a weight per unit volume of 11.9 N/m3 and a molecular mass of 0.0280 kg/mole, and is at a pressure of 1.00 atm. Number 349 Units K