Answer: The internal energy decreases by an amount of 722 kj
Explanation:
In thermodinamics we have that:
dU = dQ - dW
U is the internal energy, Q is the heat and W is the work that the system does.
this means that the change in the internal energy is equal to the change in the heat minus the change in the work.
Here we know that the system does 506kj of work and loses 266kj of heat (this means that dQ = -266kj, because the system loses heat), then we have that the total change in energy would be:
dU = -266kj - 506kj = -722kj
The internal energy decreases by an amount of 722 kj
