To measure the amount of chlorine in a well-boring fluid, an analytical chemist adds 0.210 M silver nitrate (AgNO3) solution to a 30.00 g sample of the fluid and collects the solid silver chloride (AgCl) product. When no more AgCl is produced, he filters, washes and weighs it, and finds that 1.3 g has been produced. The balanced chemical equation for the reaction is: Cl-(aq)+AgNO3(aq)-->AgCl(s)+NO3- (aq)
Calculate the mass percent of Cl in the sample. Be sure your answer has the correct number of significant digits.