Answer:
the heat gained by the system (gas) is 60 J.
Explanation:
Given;
work done by the gas sample, W = 150 J
change in internal energy, ΔU = -90 J
Apply the first law of thermodynamic;
ΔU = Q - W
where;
Q is the heat gained by the system
From the equation above;
Q = ΔU + W
Q = -90 + 150
Q = 60 J
Therefore, the heat gained by the system (gas) is 60 J.