Technetium-99 is used for brain scans. if a laboratory receives a shipment of 200 g of this isotope, how much will remain after 24 hours? the half-life of technetium-99 is 6 hours.

How many grams of aluminum will there be in 98g of al2o3?

What is the main reason why some developing countries fear the increase the free trade policies around the world?

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)