An ideal gas is compressed reversibly and isothermally so that its volume becomes half of its initial value. Which statement about the signs of heat Q, change in internal energy ΔU, and work W is correct?
a) Q>0,ΔU=0,W>0
b) Q<0,ΔU<0,W<0
c) Q<0,ΔU=0,W<0
d) Q=0,ΔU=0,W<0