Answer:
The correct options are;
a. <u>ii. Savery engine</u> The boiler could not withstand the steam pressure needed to lift water beyond 6 m.
b. <u>i.Gunpowder engine </u> The engine had no mechanism to move the piston back to complete a cycle
c. <u>iii. Newcomen engine</u> The continual reheating needed after each cooling of the engine cylinder required tremendous amount of thermal energy
d. <u>iv. Watt engine</u> This engine was large and massive and less efficient than thought possible
Explanation:
a. The evaporation of the water due to the effect of creating a vacuum limits the Savery's engine pressure differential to about 20 (which is approximately 6 meters) to 25 feet of suction
b. In The gunpowder engine after providing power to a mass, there is less provision to move the piston to a position to lift another mass
c. Energy from burning of fuel was needed to heat the steam cylinder (the steam and the steel wall) repeatedly which consumed a considerable energy in the Newcomen engine
d. In the Watt steam engine the increased efficiency attainable was 17.4% while the actual efficiency was about 11% with the addition of a separate condenser unit.