Achemistry graduate student is studying the rate of this reaction: he fills a reaction vessel with and measures its concentration as the reaction proceeds:

Answerδh > 0explanationc₆h₆  (s)  → c₆h₆ (l)if you are changing it from a solid to a liquid, you are pretty much melting the solid. this requires heat energy. therefore, the reaction is endothermic (takes in energy); the system enthalpy increases as the reaction proceeds: δh > 0.

Answer:   d.  carbon dioxide.

Answercreating graphs and performing calculations;