Dimercaprol (HSCH2CHSHCH2OH) was developed during World War I as an antidote to arsenic-based poison gas and is used today to treat heavy-metal poisoning. It binds the toxic element and carries it out of the body. (a) If each molecule binds one arsenic (As) atom, how many atoms of As could be removed by 636 mg of dimercaprol? × 10 atoms As (Enter your answer in scientific notation.) (b) If one molecule binds one metal atom, calculate the mass % of each of the following metals in a metal-dimercaprol combination: mercury, thallium, chromium. % Hg % Tl % Cr