3lf unshaded spheres represent nitrogen atoms and shaded spheres represent oxygen atoms

D.  box (c) reactants and box (d) products

Explanation:

thats a little if u want the answer just look it up on google thats what i do haha : )

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.