Uranium-235 was the first isotope that was found to be fissile. Other naturally occurring isotopes are fissionable, but not fissile. On bombardment with slow neutrons, its uranium-235 isotope will most of the time divide into two smaller nuclei, releasing nuclear binding energy and more neutrons. If too many of these neutrons are absorbed by other uranium-235 nuclei, a nuclear chain reaction occurs that results in a burst of heat or (in special circumstances) an explosion. In a nuclear reactor, such a chain reaction is slowed and controlled by a neutron poison, absorbing some of the free neutrons. Such neutron absorbent materials are often part of reactor control rods (see nuclear reactor physics for a description of this process of reactor control).
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What is used to speed a chain reaction in a nuclear reactor?
Ah, so.. unanswerable

At the end of the Second World War, Canada possessed the fourth-largest air force and fifth-largest naval surface fleet in the world, as well as the largest volunteer army ever fielded. Conscription for overseas service was introduced only near the end of the war, and only 2,400 conscripts actually made it into battle. Originally, Canada was thought to have had the third-largest navy in the world, but with the fall of the Soviet Union, new data based on Japanese and Soviet sources found that to be incorrect.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Which other country had a sizable naval army?
Ah, so.. Japanese

The FBI also spied upon and collected information on Puerto Rican independence leader Pedro Albizu Campos and his Nationalist political party in the 1930s. Abizu Campos was convicted three times in connection with deadly attacks on US government officials: in 1937 (Conspiracy to overthrow the government of the United States), in 1950 (attempted murder), and in 1954 (after an armed assault on the US House of Representatives while in session; although not present, Abizu Campos was considered the mastermind). The FBI operation was covert and did not become known until U.S. Congressman Luis Gutierrez had it made public via the Freedom of Information Act in the 1980s.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What spied on the Cuban independence leader?
Ah, so..
unanswerable