Consider the reaction
$$
2 \mathrm{~A}+\mathrm{B} \longrightarrow \mathrm{C}
$$
(a) In the diagram here that represents the reaction, which reactant, A or B, is the limiting reagent? (b) Assuming complete reaction, draw a molecular-model representation of the amounts of reactants and products left after the reaction. The atomic arrangement in C is $A B A$.