Assume that each reaction is carried out in an open container. Select a reaction for which ΔH=ΔE. H2(g)+Br2(g)→2HBr(g) C(s)+2H2O(g)→2H2(g)+CO2(g) PCl5(g)→PCl3(g)+Cl2(g) 2CO(g)+O2(g)→2CO2(g)

ΔH=ΔE+ΔngRT
Δng is the difference in the stoichiometric coefficient of products and reactants.
For ΔH=ΔE, Δng=0.
In case of option A, Δng=2-3=-1 ≠ 0. Hence, option A is incorrect.
In case of option B, Δng=2-1=1 ≠ 0. Hence, option B is incorrect.
In case of option C, Δng=2-3=-1 ≠ 0. Hence, option C is incorrect.
In case of option D, Δng=2-2=0. Hence, option D is correct.