Radioactive tungsten-178 decays with a half-life of 21.6 days. (a) What is the value of k in s-12 s-1 (b) A sample contains 29.0 mg 178w. How many decay events will be produced in the first second? Assume that the atomic mass of 178w is 178. decay events (c) A chemist obtains fresh sample of 178w and measures its radioactivity. She then determines that to do an experiment, the radioactivity cannot fall below 50.0% of the initial measured value. How long does she have to perform the experiment? days

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Micelles and Biological Membrane

Micelles are the type of lipid molecules that organize themselves in spherical shape in aqueous solutions. The production of the micelle is a reply to the amphipathic behavior of fatty acids. It means that they consist of both hydrophobic regions and hydrophilic regions. In micelles, polar head groups (hydrophilic groups) produce an outer layer associated with water whereas nonpolar tails (hydrophobic groups) are organized in the interior.