In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

An approximation of it named for Russell uses the TDS value to determine one of its parameters via the Langelier approximation, while one constant that appears in it has units of moles per kilogram to the one half power, according the Bates-Guggenheim convention. Along with Guggenheim, Scatchard and Bronsted improved upon this model by developing the SIT theory, and that model has a better fit than a modification of it named for Davies. This relationship assumes the existence of only long-range interactions, and it was extended to account for Brownian motion by Lars Onsager. It assumes that the solvent is structure-less and that the solution is dilute, and the theory behind it implies that the electrostatic potential falls off exponentially when r is greater than the atomic radius due to screening by counter ions. For 10 points, identify this equation which is used to calculate the activity coefficients, and is named for a German and a Dutch scientist.
Science

He ended his life as king of Illyricum and went to Elysium after he and his wife fulfilled a prophecy. This son of Telephassa and Agenor, the rulers of Phoenicia, succeeded at a task in which his four brothers could not. At the end of his life he and his wife Harmonia are turned into snakes, but this has occurred well after he has sown some dragon's teeth. FTP, name this brother of Europa and founder of Thebes.
Social Science

One compound that is sometimes mistaken for this resource is created by crushing jatropha seeds. Companies such as Lignol and Novozymes have worked to create the "cellulosic" form of this resource from wood chips. Support for American production of this resource has led to decreased use of MTBE, and previously spurred on a controversial 54-cent tariff on (*) imports of this resource from its most extensive user. Concerns about food prices have caused criticisms about the use of land to produce this resource, which powers automobiles in Brazil. For 10 points, name this petroleum substitute that is often made of sugarcane or corn.
Science