What is the maximum mass of the lower molar mass product that can be formed when 83.0 g of solid barium bromide and 20.5 g chlorine gas react?
See your other LR problems. The lower molar mass material is Br2.
However, I have some real problems with this problem; SOLIDS don't react that well and unless the reactions is stirred so that all of the BaBr2 can react I don't know that you can attain the theoretical yield.