26. Which of the following statements is true about heat engines?
A) Heat engines convert heat completely into work
B) Heat engines violate the first law of thermodynamics
C) Heat engines are always more efficient than refrigerators
D) Heat engines convert some heat into work and some into waste heat
Answer: D) Heat engines convert some heat into work and some into waste heat
27. The efficiency of a Carnot engine operating between two temperatures is given by:
A) 1 – T1/T2
B) T1/T2
C) (T2 – T1)/T2
D) (T2 – T1)/T1
Answer: C) (T2 – T1)/T2
28. Which of the following is an example of a heat pump?
A) A refrigerator
B) A stove
C) A light bulb
D) A space heater
Answer: A) A refrigerator
29. Which of the following materials has the lowest thermal conductivity?
A) Aluminum
B) Glass
C) Wood
D) Air
Answer: D) Air
