Apencil exerts downward force on a table due to its
a) weight
b) volume
c) normal force
d) reaction force

Weight
i think, because without weight, it would not be right 

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.