The enthalpy of an intermediate step should be manipulated when used to produce an overall equation by using the Hess's law. You could multiply the enthalpy by -1 if this equation is reversed in theory.
I would say D. Let me know if i am wrong.
Answer:
Answer: A. Gases are easily compressed because of the low density.
Explanation:
This link might help you!!
https://www.eiu.edu/biology/bio1500/writing_a_lab_report.pdf
Oxygen gas was most likely absent from Earth's primitive atmosphere. The current theory is that the Earth's early atmosphere was composed of mainly carbon dioxide and methane due to the high volcanic activity. Cyanobacteria and their use of photosynthesis was what caused earth's atmosphere to become oxygen enriched.
I hope that helps.