Question

5 J of heat is taken out of the system and 20 J of work is done on the system, what is the change in internal energy of the system?

(a) 5 J

(b) 10 J

(c) 15 J

(d) 20 J

The question was posed to me by my college director while I was bunking the class.

My doubt stems from Energy Balances for Closed, Unsteady-State Systems in division Introduction to Energy Balances for Processes without Reaction and Calculation of Enthalpy Changes of Basic Chemical Engineering

Answer 1

Right answer is (c) 15 J

Easiest explanation: ∆U = 20 – 5 = 15 J.