Nuclei-Quiz-10

NUCLEI QUIZ-10

Dear Readers,

JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts.

Q1The electron emitted in beta radiation originates from

•   Inner orbits of atoms
•   Free electrons existing in a nuclei
•   Decay of a neutron in a nucleus
•   Photon escaping from the nucleus

Solution 

(c) We know that in a nucleus, neutron converts into proton as follows: n→p^+→e^- Thus, decay of neutron is responsible for β-radiation orgination

Q2The minimum frequency of a γ-ray that causes a deuteron to disintegrate into a proton and a neutron is (m_d=2.0141 a.m.u.,m_p=1.0078 a.m.u.,m_n=1.0087 a.m.u)

•   2.7×10^20 Hz
•   5.4×10^20 Hz
•   10.8×10^20 Hz
•   21.6×10^20 Hz

Solution

Q3Let E_1 and E_2 be the binding energies of two nuclei A and B. It is observed that two nuclei of A combine together to form a B nucleus. This observation is correct only if

•   E_1>E_2
•   E_2>E_1
•   E_2>2E_1
•   Nothing can be said

Solution 

(c) Transformation occurs only when the same net energy is released, which is possible only when E_2>2E_1

Q4If mass of 〖 _ U〗^235=235.12142 a.m.u., mass of 〖 _ U〗^236=236.1205 a.m.u. and mass of neutron =1.008665 a.m.u., then the energy required to remove one neutron from the nucleus of 〖 _ U〗^236 is nearly about

•   75 MeV
•   6.5 MeV
•   1 eV
•   Zero

Solution

Q5. In fission, the percentage of mass converted into energy is about

•   10%
•   1%
•   0.1%
•   0.01%

Solution

Q6. The energy released in a typical nuclear fusion reaction is approximately

•   25 MeV
•   200 MeV
•   800 MeV
•   1050 MeV

Solution

Q7. Mark out the incorrect statement

•   A free neutron can transform itself into photon
•   A free proton can transform itself into neutron
•   In beta minus decay, the electron originates from nucleus
•   All of the above

Solution (a) When a free neutron decays to a proton along with an electron and an antineutrino, the Q value of the reaction is positive which means the reaction is possible all by itself, while a free proton cannot convert itself into a neutron due to negative Q value In beta minus decay, the electron originates from nucleus only, by the transformation of neutron into a proton, with simultaneous emission of an antineutrino

Q8 For uranium nucleus how does its mass vary with volume?

•   m∝ V
•   m∝ 1/V
•   m∝√V
•   m∝V^2

Solution 

(a) Nuclear density is constant hence, mass ∝ volume Or m∝ V

Q9An element X decays, first by positron emission and then two α-particles are emitted in successive radioactive decay. If the product nucleus has a mass number 229 and atomic number 89, the mass number and atomic number of element X are

•   237, 93
•   237, 94
•   221, 84
•   237, 92

Solution

Q10. At any instant, the ratio of the amounts of two radioactive substances is 2:1. If their half-lives be, respectively, 12 h and 16 h, then after two days, what will be the ratio of the substances?

•   1:1
•   2:1
• 1:2
• 1:4
  
  

Solution