Describe the process by which energy is generated in the CORE of the Sun; i. e. basically describe the entire photon-photon chain reaction in detail. You are not being asked to discuss how energy from the Sun gets from the inside, through the layers, to the outside...you are looking to describe the step-by-step details of the proton-proton chain reaction!

d

explanation:

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.