You can’t touch yesterday
So why let yesterday touch you

a. a primary source combines several different accounts of an event. b. a primary source generally benefits from having been written after an event.

explanation:

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.

answer; natural resources;