Hello,
For the reaction described below the questions asks for the activation energy. Two of the answers options are:
a)the activated complex minus the energy of the products.
b)the activated complex minus the energy of the reactants.
I think option a is describing a endothermic reaction and option b is describing a exothermic reaction. My question is based on the passage how can you tell if the reaction is exothermic or endothermic.

Passage:
Iodine and zinc are the reactants in an experiment to find the stoichiometry of a reaction. Gray, granular zinc metal (2.0 g) and purple iodine crystals (2.0 g) are added to an Erlenmeyer flask containing 25 mL of methanol (CH3OH). The iodine dissolves in the methanol giving a red-brown solution. After 15 min of heating, the solution is pale yellow, and a few gray granules remain at the bottom of the flask. The liquid is decanted into a beaker. The remaining granules are rinsed several times with methanol, and the methanol from each rinse is added to the beaker. The methanol is then evaporated, leaving a solid, yellow-white product of iodide of zinc. The mass of the dry product is obtained. The unreacted zinc granules are also dried and weighed.

A 2:1 ratio of moles of iodine atoms to zinc atoms in the product is consistently obtained. The mass of iodine and reacted zinc equals the mass of product.

Thank you!