Chemistry · THERMODYNAMICS

Which of the following conditions represents the exact state where \( \Delta H = \Delta U \) for a chemical reaction involving gases?

1. The reaction is conducted at extremely high pressures so that ideal behavior is severely departed from.
2. The reaction occurs in an open vessel at constant external atmospheric pressure.
3. The reaction is highly exothermic such that \( q_p < 0 \).
4. The difference between the number of moles of gaseous products and gaseous reactants (\( \Delta n_g \)) is identically zero.