201. The 92U238 emits an a-particle. The product is
202. Graphite is used in nuclear reactor as
203. The half life period of a radioactive element depends on its
204. __________ have the same mass number, but different nuclear charge.
205. Which one is radioactive in nature ?
206. Absorption/scattering cross-section of an element is expressed in "barn", which is equivalent to
207. The most commonly used nuclear fuel in boiling water reactor is
208. Nuclides having the same atomic numbers are termed as
209. The number of neutrons accompanying the formation of 54Xe139 and 38Sr94 from the absorption of a slow neutron by 92U235 , followed by nuclear fission is
210. A fertile material is the one, which can be
211. Fast breeder nuclear reactors using enriched uranium as fuel may contain upto a maximum of __________ percent of U-235 (i.e. fissile material).
212. Thorium metal
213. Enrichment of uranium is done to increase the concentration of __________ in the natural uranium.
214. Atoms with same number of neutrons, but different number of nucleons are called
215. Which of the following ores contains maximum percentage of uranium ?
216. Uranium ore is currently mined & concentrated at
217. How many atoms are present in one gm-atom of an element ?
218. Emission of β-particles during radioactive decay of a substance is from
219. Percentage of U-238 in natural uranium is around
220. A fast breeder reactor employs
221. Which of the following may be used to measure the rate of nuclear disintegration?
222. The decrease in the atomic number is not observed in case of
223. The mass number of an element is not changed, when it emits __________ radiations.
224. Which of the following is not a naturally occurring nuclear fuel ?
225. An electron has a mass that is approximately __________ that of the proton.