If a has a free energy of 38 units, and c has a free energy of 45 units, and the reaction is exergonic, based on the calculation of free energy, which is the substrate and which is the

C is the substrate

A is the product

Explanation:

Exergonic reactions are the ones that release energy during the course of the conversion of substrates into the products. The free energy content of the substrates of exergonic reactions is higher than that of their products. This excess energy is released during the reaction. In the given reaction, the free energy content of C is 45 units which is higher than the free energy content of A (38 units). This means that the substrate "C" has undergone an exergonic reaction and is being converted into the product "A".

weathering is the answer.