)which one of the following statements best describes the operation of a heat engine?
a) a heat engine performs work and generates an equal amount of thermal energy in a cyclic process.
b) a heat engine decreases the entropy of the universe by generating an equal amount of heat and work.
c) a heat engine uses input heat to perform work and rejects excess thermal energy to a lower temperature reservoir.
d) a heat engine transfers thermal energy from a lower temperature reservoir to a higher temperature reservoir through work performed on the system.
e) a heat engine transfers thermal energy from a higher temperature reservoir to a lower temperature reservoir through work performed on the system

Option C is correct.

A heat engine uses input heat to perform work and rejects excess thermal energy to a lower temperature reservoir.    

Explanation:

Option C is correct.

If we look into Second law of thermodynamics it is impossible for heat engine to convert heat energy completely into work without losing some heat to cold reservoir.

Heat engines convert thermal energy into mechanical energy by taking heat from hot reservoir converting some heat to work and releasing remaining heat to cooled reservoir.

Note:

All other options are incorrect because they defy Second Law of thermodynamics.

hi there!

out of the two, (b) precision would be more reasonable.   however, both a and b could be pretty reasonable.

-awesomerepublic   : )