Question

10 J of heat is supplied and 3 J is taken out, if the change in internal energy of the system is 5 J, what is the work done on the system?

(a) 2 J

(b) – 2 J

(c) 5 J

(d) – 5 J

This question was addressed to me in unit test.

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

Answer 1

Correct choice is (b) – 2 J

Explanation: 5 = 10 – 3 + W, => W = – 2 J.