Question: Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. While uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons, uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors, and produces the fissile material for nuclear weapons. Depleted uranium (238U) is used in kinetic energy penetrators and armor plating.
Is there an answer to this question: What is the sole fissile isotope that occurs in nature?

Answer: Uranium-235

Question: In physics, degenerate matter refers to the ground state of a gas of fermions at a temperature near absolute zero. The Pauli exclusion principle requires that only two fermions can occupy a quantum state, one spin-up and the other spin-down. Hence, at zero temperature, the fermions fill up sufficient levels to accommodate all the available fermionsand in the case of many fermions, the maximum kinetic energy (called the Fermi energy) and the pressure of the gas becomes very large, and depends on the number of fermions rather than the temperature, unlike normal states of matter.
Is there an answer to this question: What depends on the temperature at absolute zero?

Answer: unanswerable

Question: At over 5 million, Puerto Ricans are easily the 2nd largest Hispanic group. Of all major Hispanic groups, Puerto Ricans are the least likely to be proficient in Spanish, but millions of Puerto Rican Americans living in the U.S. mainland nonetheless are fluent in Spanish. Puerto Ricans are natural-born U.S. citizens, and many Puerto Ricans have migrated to New York City, Orlando, Philadelphia, and other areas of the Eastern United States, increasing the Spanish-speaking populations and in some areas being the majority of the Hispanophone population, especially in Central Florida. In Hawaii, where Puerto Rican farm laborers and Mexican ranchers have settled since the late 19th century, 7.0 per cent of the islands' people are either Hispanic or Hispanophone or both.
Is there an answer to this question: What is the second largest hispanic group?

Answer: unanswerable

Question: Since genomes are very complex, one research strategy is to reduce the number of genes in a genome to the bare minimum and still have the organism in question survive. There is experimental work being done on minimal genomes for single cell organisms as well as minimal genomes for multi-cellular organisms (see Developmental biology). The work is both in vivo and in silico.
Is there an answer to this question: What do scientists want a silico to do in the experiment?

Answer:
unanswerable