Based on the enthalpy changes given for the reactions, which reactions are endothermic? (check all that apply) 2h2o → 2h2 + o2, δh = 484 kj c + o2 → co2, δh = -394 kj h2 + br2 → 2hbr, δh = -73 kj 2nh3 → n2 + 3h2, δh = 92 kj

In an endothermic reaction, “delta H” is always positive, since the system is absorbing heat from its surroundings, not releasing into the surroundings like in an exothermic reaction where the delta H is always negative.

So our endothermic reactions would be the first (484kJ) and the last (92kJ).

They carry out the exchange of gases as we breathe ( oxygen and carbon dioxide).

It has to be b i hope this