A mixture of KBr and NaBr weighing 0.560 gm was treated with aqueous Ag⁺ and all the bromide ion was recovered as 0.970 gm of pure AgBr. The weight of KBr in the sample is

This question uses stoichiometry and limiting reagent. Write the balanced chemical equation, compute moles of each reactant, identify the limiting reagent, and use stoichiometric ratios (and % yield, if needed) to obtain the answer; this gives option B.