Sometimes models are not draw to scale (the exact right size). In the image po above all eras are the same size... but should they be? Which of the
following eras lasted approximately 290 million years
Paleozoic
Mesozoic
Cenozoia
Cambrian

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.