Tell whether reactions with the following values of ^H and ^S are spontaneous or nonspontaneous and whether they are exothermic or endothermic: (a) ^H = -128kj; ^S = 35J/K at 500K (b) ^H = +67KJ; ^S= -140J/K at 250K (c) ^H = +75kJ; ^S = 95 J/K at 800K