The refractive index of water with respect to air is 1∙33. What will be the refracted angle of light at water when light incident at an angle 45° in air? (a) 28∙6° (b)36∙4°
(c)32∙11°
(d)14.3°​

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.