Which of the following changes would make a heat engine less efficient?

a. a decrease in its exhaust temperature
b. a decrease in entropy
c. an increase in work done
d. a decrease in its operating temperature

Which best describes the first law of thermodynamics as compared to the second law of thermodynamics? a. the first law describes how thermal energy is conserved but not the direction it moves. b. the first law describes the direction thermal energy moves but not how it is conserved. c. the first law describes how thermal energy can be created but not how it can be destroyed. d. the first law describes how thermal energy can be destroyed but not how it can be created.