Which of the following is a characteristic of a mixture?
a. it has varying properties.
b. it has a fixed composition
c. it contains only pure substances
d. it has both varying properties and a fixed composition

Dshould be the answer to the question

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.