Final answer:
Using the first law of thermodynamics, the change in internal energy is calculated as the heat absorbed by the system minus the work done by the system, resulting in a change of (a) 300J.
Step-by-step explanation:
The question deals with the concept of the first law of thermodynamics, which states that the change in internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system on its surroundings. The formula can be represented as:
ΔU = Q - W
In this problem, we are given that a system absorbs 600J of heat (this is Q) and does 300J of work on its surroundings (this is W). Substituting these values into the formula, we get:
ΔU = 600J - 300J
ΔU = 300J
Therefore, the change in internal energy of the system is 300J.