QUESTION: Why do the following materials not react? Pb(NO3)2 + Cu → No Reaction
Because Copper is more active than the Lead in the compound.
Because Copper is less active than the Lead in the compound.
Because Copper is more active than the Nitrate in the compound.
Because Copper is less active than the Nitrate in the compound.

the answer would be b i believe

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.