Which statement most accurately explains why atp hydrolysis is highly exergonic?
a. there is a large drop in potential energy because charge repulsion is reduced
b. there is a large increase in potential energy because charge repulsion is reduced.
c. atp contains the carbohydrate ribose which stores a large amount of chemical energy.
d. energy is released when a phosphate group is added.

a. There is a large drop in potential energy because charge repulsion is reduced

Explanation:

Adenosine triphosphate, or ATP, is a relatively simple small molecule. This can be considered as the main energy currency of cells, just as money is the main economic currency of human societies. The energy released by the hydrolysis (degradation) of ATP is used to drive many cellular reactions that require energy.

Phosphoanhydride bonds are considered to be high energy, because there is a large drop in potential energy because charge repulsion is reduced, this really means that an appreciable amount of energy is released when one of these bonds is broken in a hydrolysis reaction (water-mediated rupture). ATP is hydrolyzed to ADP in the following reaction:

ATP + H2O ⇄ ADP + Pi + energy

where Pi represents an inorganic phosphate group

Like most chemical reactions, the hydrolysis of ATP in ADP is reversible. The reverse reaction, which regenerates ATP from ADP and Pi requires energy. ATP regeneration is important because cells tend to use (hydrolyze) ATP molecules very quickly and depend on the ATP being constantly replaced.