Which two particles make up most of the mass of a hydrogen-2 atom?
(1) electron and neutron
(2) electron and proton
(3) proton and neutron
(4) proton and positron

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.

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Energy defines the different "states" of matter. in no more than 3 sentences, describe the amount of kinetic energy that each of the 3 states of matter possesses and relate that to the atom/molecular motion of each "state".