The first law of thermodynamics states ΔU=Q+W, where
A.
W >0 when work is done by surroundings.
B.
W >0 when work is done by system.
C.
W <0 when work is done by surroundings.
D.
Q >0 when heat is gained by surroundings.
E.
Q <0 when beat is gained by system.