The maximum kinetic energy of the electron emited from a metallic surface is 1.6x10 to the power -19 J when the frequency of radiation is 7.5 × 10 to the power-14 Hg. calculate of minimum frequency of radiation for which radiation is emited

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.