Reaction Enthalpies HW Q49

[Julie Barreto 3A]

The question asks for the internal energy for the reaction of 1.00 mol. I understand that you use the internal energy equation. But how do you know if the reaction is in constant pressure or not. How do you know for which questions you can use qp or just q.?

[Alexandra_Ivanova_1A]

Since no pressure or volume is indicated, we use PV=nRT to find PV and then find the change in internal energy for the rxn by using the equation:
(delta U)=(delta H)-(PV). Since the reaction is at standard conditions, I think we assume the pressure is constant.