In a hypothetical city such as gotham city, the temperature is dropping and the skies are clearing. how would the barometer be changing?

The barometer would show a decrease in wind speed resulting in the disipation of cloud cover because of the lack of wind, and also because the temperature is dropping there is less precipation because there is no hot air rising to create clouds :)

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.