Question

Energy out and Energy in of a system are 10 J and 25 J respectively, what is the efficiency of the system?

(a) 10%

(b) 40%

(c) 50%

(d) 80%

This question was posed to me in a national level competition.

My doubt stems from Efficiency topic in chapter Energy Balances that Include the Effects of Chemical Reaction, Ideal Processes, Efficiency and the Mechanical Energy Balance and Heats of Solution and Mixing of Basic Chemical Engineering

Answer 1

Right answer is (b) 40%

For explanation: Efficiency = 10/25*100 = 40%.