tailieunhanh - Toefl preparation for the computer and paper test part 47

Tham khảo tài liệu 'toefl preparation for the computer and paper test part 47', ngoại ngữ, toefl - ielts - toeic phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 444 READING 4. The following sentence could be added to paragraph 2. They enjoyed the comfort of performing in underwear rather than costumes. Where would it best fit into the paragraph Click on the square to add the sentence to the paragraph. 5. The following sentence could be added to paragraph 3. It was a taste sensation that stayed on his mind. Where would it best fit into the paragraph Click on the square to add the sentence to the paragraph. PASSAGE THREE Questions 6-7 Uranium a radioactive metal named after the planet Uranus is a primary source of energy in nuclear power plants and certain nuclear weapons. It occurs naturally in three different isotopes which differ in their facility in undergoing nuclear fission. Line S3 The three naturally occurring isotopes of uranium are U-234 U-235 and U-238. QJ Each 5 of these isotopes has the same atomic number of 92 which is the number of protons in the nucleus. EQ However each has a different number of neutrons and thus has a different atomic mass which is the sum of the number of protons and neutrons. Q3 Of these three naturally occurring isotopes of uranium U-238 is by far the most common while U-235 is the most capable of undergoing nuclear fission. Q More than 99 of all naturally 10 occurring uranium is U-238 while U-234 and U-235 each make up less than 1 . Q3 Nuclear fission can occur when a U-235 nucleus is struck by a neutron and the nucleus splits releasing energy and releasing two or more neutrons. E3 However nuclear fission rarely involves a U-238 nucleus or a U-234 nucleus because it is unusual for either of these nuclei to break apart when struck by a neutron. Q9 6. The following sentence could be added to paragraph 2. U-234 has 92 protons and 142 neutrons for an atomic mass of 234 U-235 has 92 protons and 143 neutrons for a total of 235 and U-238 has 92 protons and 146 neutrons for a total of 238. Where would it best fit into the paragraph Click on the square to add the sentence to the paragraph. 7. The