Answer: a) 85% of the reactants were used up
b) True
Step-by-step explanation:
Percentage yield is defined as the ratio of actual yield to theoretical yield in terms of percentage. The actual yield is the amount of product obtained after the experiment and the theoretical yield is the amount of ideal product that should have been obtained.
Formula :

Thus 85 % yield means 85 % of the reactants were used up to give only 85% of products.
The limiting reactant is the reactant that limits the amount of product formed and hence is completely used up after the reaction is complete. Thus the given statement is True.