6. Making which of the following changes to the steam engine will
increase its efficiency?
a. Increasing the exhaust temperature
b. Decreasing the exhaust temperature
C. Increasing the amount of heat input
d. Decreasing the amount of heat input
-7. The amount of useful work that can be generated from a source
of heat can only be
a. less than the amount of heat
b. less than or equal to the amount of heat
c. equal to the amount of heat
d. equal or greater than the amount of heat​