The arrangement of atoms at the peak of the activation energy barrier is known as the
a. activation rate
c. transition state
d. both b and c

The arrangement of atoms at the peak of the activation energy barrier is known as the transition state. The correct option among all the options that are given in the question is option "C". I think you forgot to give the second option in the question. I hope that this is the answer that has come to your help.

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.