The correct option is D 2NO2(g)+→N2O4(g)
We know,
ΔH=ΔU+ΔngRT
So when, Δng=(np−nr)g=0 ⇒ΔH becomes equal to ΔU.
for (a)
Δng=(np−nr)g=0
for (b)
Δng=(np−nr)g=−2
for (c)
Δng=(np−nr)g=−2
for (d)
Δng=(np−nr)g=−1
We can clearly see for (b), (c), (d)
Δng=(np−nr)g is not equal to 0
so, for these cases,
ΔH is not equal to ΔU.