NUCLEI QUIZ-20
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.
Q1. Statement 1: The fission of a heavy nucleus is always accompanied with the neutrons along with two product nuclei
Statement 2: For a lighter stable nuclide, the N/Z ratio has to be slightly greater than 1
Q2. Statement 1: Radioactive nuclei emits β^(-1) particles
Statement 2: Electrons exist inside the nucleus
Solution
(c)
Nuclear stability depends upon the ratio of neutron to proton. If the n/p ratio is more than the critical value, then a neutron gets converted into a proton forming a β^- particle in the process n→p+e^-
The β^- particle (e^-) is emitted from the nucleus in some radioactive transformation. So electrons do not exist in the nucleus but they result in some nuclear transformation
Q3.Statement 1: A certain radioactive substance has a half-life period of 30 days. Its disintegration constant is 0.0231 day ^(-1)
Statement 2: The decay constant is related with half-life λ=0.6931/T
Solution
Q4.Statement 1: _38 Sr^90 from the radioactive fall out from a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells
Statement 2: The energy β-particle emitted in the decay of ^90 Sr damage to bone marrow
Solution
(a)
_38 Sr^90decays to _39 Y^90when β-rays emission is occurred. Sr gets absorbed in bones along with calcium which causes impairment of the production of red blood cells. So, assertion is true.
Now, Sr^90 □(→┴( β ) Y^90 )
Sr decays to Yttrium Sr ^90emits β-rays of very high energy. Bone marrow is damaged by these high energetic β-particles. So, reason is also true
Q5.
Statement 1: The ratio of time taken for light emission from an atom to that for release of nuclear energy in fission is 1 : 100.
Statement 2: Time taken of the light emission from an atom is of the order of 10^(-8) s.
Solution
(c)
According to postulates of Bohr’s atom model, the electron revolves around the nucleus in fixed orbit of definite radii. As long as the electron is in a certain orbit it does not radiate any energy
Q6.Statement 1: Electrons in the atom are held due to coulomb forces
Statement 2: The atom is stable only because the centripetal force due to Coulomb’s law is balanced by the centrifugal force
Solution
(c)
According to postulates of Bohr’s atom model, the electron revolves around the nucleus in fixed orbit of definite radii. As long as the electron is in a certain orbit it does not radiate any energy
Q7.Statement 1: Amongst alpha, beta and gamma rays, α-particle has maximum penetrating power
Statement 2: The alpha particle is heavier than beta and gamma rays
Solution
(d)
The penetrating power is maximum in case of gamma rays because gamma rays are electromagnetic radiations of very small wavelength
Q8. Statement 1: Radioactivity of 10^8 undecayed radioactive nuclei of half life of 50 days is equal to that of 1.2×10^8 number of undecayed nuclei of some other material with half life of 60 days
Statement 2: Radioactivity is proportional to half-life
Q9. Statement 1: The positively charged nucleus of an atom has a radius of almost 10^(-15) m
Statement 2: In α-particle scattering experiment, the distance of closest approach for α-particles is ≃10^(-15) m
Solution
(a)
In α-particle scattering experiment, Rutherford found a small number of α-particles which were scattered back through an angle approaching to 180°. This is possible only if the positive charges are concentrated at the centre or nucleus of the atom
Q10. Statement 1: ^90 Sr from the radioactive fall out from a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells.
Statement 2: The energetic β-particles emitted in the decay of ^90 Sr damage the bone marrow.
Solution
(b)
1. If Assertion is True, Reason is True, Reason is correct explanation of 1
2. If Assertion is True, Reason is True, Reason is not correct explanation of 1
3. If Assertion is True, Reason is False
4. If Assertion is False, Reason is True
