Question

Activity 27-4. Nuclear fission (Accompanies Section 27-4] 1 A uranium nucleus (235U) absorbs a neutron. The result is a uranium nucleus (236U) in an excited state. 3 The excited uranium nucleus fissions into two smaller, more tightly bound nuclei... ...as well as a few neutrons. These can trigger the fission of other 235U nuclei. 3 neutrons Neutron + 2350 236U 134 Te 9976 Z = 0 protons Z = 92 protons N = 1 neutron N = 143 neutrons A=Z+N A=Z+N = 1 nucleon = 235 nucleons Z = 92 protons N = 144 neutrons A=Z+N = 236 nucleons Z = 52 protons N = 82 neutrons A = Z+N = 134 nucleons Z = 40 protons N = 59 neutrons A = Z+N = 99 nucleons Z = 0 protons N = 3 neutrons A=Z+N = 3 nucleons Energy is released in this fission reaction: The total kinetic energy of the fission fragments is much greater than the total kinetic energy of the initial neutron and 23SU nucleus. The illustration shows one possible way that a nucleus of uranium-235 (235U) can undergo neutron-induced fission. (a) Rank the following objects in order of their binding energy per nucleon, from largest to smallest. If any two objects have the same binding energy per nucleon, state this. Explain how you made your ranking: (i) The uranium-235 (235U) nucleus (ii) The tellurium-134 (134Te) nucleus (iii) The zirconium-99 (99Zr) nucleus (iv) The three neutrons Activity 27-4 [continued]. (b) Using your results from part (a), explain why energy is released in the neutron-induced fission of 235U shown in the figure on the preceding page. (c) Once the 236U* nucleus fissions, the 134Te nucleus and "Zr nuclei actually accelerate away from each other. What is the force that causes this acceleration? Explain your reasoning. (i) The strong nuclear force that acts between the individual nucleons of the 134Te nucleus (ii) The strong nuclear force that acts between the individual nucleons of the 99Zr nucleus (iii) The strong nuclear force that acts between the 134Te nucleus and the 99Zr nucleus (iv) The electric force that acts between the individual protons of the 134Te nucleus (v) The electric force that acts between the individual protons of the '9Zr nucleus (vi) The electric force that acts between the 134Te nucleus and the 99Zr nucleus (vii) More than one of the above

Answer 1

a. We know that, binding energy per nucleon depends on the Mass number and decreases with mass number after mass number of about 60
hence, From the given data
235 U, 236 U , 134 Te, 99 Zr, and 3 neutrons.
The 3 neutrons have no binding energy
so,
the ranking in terms of binding energy from maximum to minimum is as under
99 Zr > 134 Te > 235 U > 236 U > 3 Neutrons

b. In the neutron induced fission,
we can see that a higher atomic mass 236 U becomes a lower atomic mass 134Te and 99 Zr
since the extra 3 neutrons have no binding energy and Binding energy is -ve and above sequence is based on magnitude
so, when a lower binding energy Uranium becomes higher binding energy atoms, the systems energy increases, in negative, so in total the system energy decreases
hence the leftover energy is released inthe fission
  
c. 134Te and 99Zr steer away because of coloumbs repulsion of the constutent groups of protons in both the atoms
  
hence option iv. The electric force that acts between athe nuclei of botht the atoms