Several different types of models can be used to represent the particles in a substance. Model 1: Two-dimensional illustration of a water molecule.
Model 2: Three-dimensional block model of a water molecule
Model 3:Three-dimensional ball-and-stick model of a water molecule

What information described in models 1 and 3 is absent in model 2?

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.