The energy required to initiate an exergonic reaction is called

energy of activation is the correct answer.

Explanation:

All the chemical reactions including an exothermic reaction require activation energy to initiate a reaction.Activation energy is the minimum amount of energy required to activate the molecules to the situation that they can experience a chemical change. If the activation energy is lower the faster the reaction occurs.Joules, kilocalories/mol, kilojoules per mole are the units for activation energy.

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.