Only do the 10, 13, 15, 16,18 ,& 21

The answer is a) carbon-12

Thermohaline circulation and gyres

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.