TASK DEFINITION: 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.
PROBLEM: The electron dipole moment of this particle is at most three times ten to the negative 26th, and would violate CPT-symmetry if it is non-zero. This particle has a half-life of 881 seconds, and can break up into a proton, an electron and an electron antineutrino via beta decay. This particle is composed of one (*) up and two down quarks, and nuclear fission is initiated by the bombardment of this particle. The number of this particle dictates what isotope an atom is, and they have mass roughly equal to that of a proton. James Chadwick discovered, for ten points, what particle found in the nucleus, which, as its name suggests, has a net charge of zero

SOLUTION: Science

PROBLEM: One member of this phylum, Strongylocentrotus purpuratus, is often used to study developmental processes, and another, Pisaster ochraceus, is an example of a keystone species. Most members of this phylum have pedicellariae that possess three jaws, and some have a chewing apparatus known as Aristotle's lantern. Members of class Asteroidea of this phylum have an ambulacral groove, and the madreporite is the entrance to their water vascular system that includes tube feet. FTP name this phylum whose "spiny skinned" members have radial symmetry and include sand dollars, sea urchins, and sea stars.

SOLUTION: Social Science

PROBLEM: This property is displayed by ProHance, Optimark, and other Gadolinium-containing MRI contrast agents. HAMR drives curcumvent the size limits for one form of this phenomenon, and that form has a relaxation time proportional to the exponential of the nanoscale anisotropy times the volume, according to the Arrhenius-Neel law. On a bulk scale, ferrofluids display the super- version of this phenomenon. This phenomenon is proportional to the hyperbolic tangent of mu B over k T according to the Langevin law, which in one regime reduces to M equals C times B divided by T, a law named for Curie. This phenomenon occurs above the Curie point in some materials, and materials that exhibit it have positive magnetic susceptibility. For 10 points, name this type of magnetism in which domains will weaky align with an applied field.

SOLUTION:
Science