During the power stroke of an internal combustionengine, the air-fuel mixture is ignited and the expanding hot gasespush on the piston. Fuel efficiency is maximized in this processwhen the ignited gas is as hot as possible, the gas expandsallowing a maximum amount of work to be done, and cooled exhaustgas is released at the end of the cycle. Assuming the engineexhibits the highest efficiency possible, which of the followingstatements concerning the exhaust gas must be true to avoidviolating the second law of thermodynamics?
The exhaust gas must be cooled to the same temperature as theoutside air.
The exhaust gas must be at the same pressure as the outsideair.
The exhaust gas must be hotter than the outside airtemperature.
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The exhaust gas must be at the same volume as the outsideair.
A tray of water is placed into a freezer. As the watercools, its entropy decreases and eventually it turns to ice. Whydoesn’t this process violate the second law ofthermodynamics?
The entropy of the water decreases, but upon freezing itincreases to its previous value.
The process as described does violate the second law ofthermodynamics.
The overall entropy increases due to the refrigerator chillingand eventually freezing the water.
When the ice is later taken out and melted, the entropy willincrease back to what it was before the tray was put into thefreezer
