QUESTION 20 An ideally efficient heater adds 997 J of heat to a warm room. How much work does it take in if it removes 505 J of energy from the outdoors? QUESTION 21 A heat engine having an efficiency of 0.22 takes in 1954 J of energy from the hot reservoir in one cycle. In the same time, how much work will it perform? QUESTION 22 A heat engine takes in 890 J of energy from the hot reservoir in one cycle and does 681 J of work. What is the engine's efficiency (NOT as a percentage)