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#1 Class 12 Physics Nuclei 2019 Mcq 1M CBSE
The radius of a nucleus is proportional to
A. $A$
B. $A^2$
C. $A^3$
D. $A^{1/3}$
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#2 Class 12 Physics Nuclei 2021 Mcq 1M CBSE
Which of the following statements about nuclear forces is NOT true?
A. Nuclear force falls rapidly to zero for distance > few femtometres
B. Nuclear force is much weaker than Coulomb force
C. Force is attractive for $r > 0.8$ fm and repulsive for $r < 0.8$ fm
D. Nuclear force between n-n, p-n and p-p is approximately the same
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#3 Class 12 Physics Nuclei 2022 Long 1M CBSE
Assertion (A): Nuclei having mass number about 60 are most stable. Reason (R): When two or more light nuclei are combined into a heavier nucleus, the binding energy per nucleon decreases.
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#4 Class 12 Physics Nuclei 2021 Mcq 1M CBSE
The ratio of the nuclear densities of two nuclei having mass numbers 8 and 27 is
A. 08:27
B. 03:02
C. 02:03
D. 01:01
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#5 Class 12 Physics Nuclei 2022 Long 1M CBSE
Assertion: Energy is released in nuclear fission. Reason: Total binding energy of the fission fragments is larger than the total binding energy of the parent nucleus.
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#6 Class 12 Physics Nuclei 2021 Long 1M CBSE
Assertion: Between any two given energy levels, the number of absorption transitions is always less than the number of emission transitions. Reason: Absorption transitions start from the lowest level only and may end ...
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#7 Class 12 Physics Nuclei 2022 Long 1M CBSE
Assertion: Isobars are elements having same mass number but different atomic number. Reason: Neutrons and protons are present inside the nucleus.
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#8 Class 12 Physics Nuclei 2021 Mcq 1M CBSE
An element has binding energy 8 eV per nucleon. If it has a total binding energy of 128 eV, then the number of nucleons is
A. 8
B. 16
C. 32
D. 64
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#9 Class 12 Physics Nuclei 2019 Short 1M CBSE
For a uranium nucleus, how does its mass vary with volume?
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#10 Class 12 Physics Nuclei 2020 Mcq 1M CBSE
Which of the following is an essential requirement for initiating a fusion reaction?
A. critical mass
B. thermal neutrons
C. high temperature
D. critical temperature
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#11 Class 12 Physics Nuclei 2018 Mcq 1M CBSE
Elements with the same atomic mass but different atomic number are called
A. isobars
B. isotones
C. isotopes
D. isochores
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#12 Class 12 Physics Nuclei 2019 Mcq 1M CBSE
Isotopes have
A. same atomic number and mass number
B. same mass number but different atomic number
C. different atomic number and mass number
D. same atomic number but different mass number
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#13 Class 12 Physics Nuclei 2020 Mcq 1M CBSE
As mass number $A$ increases, which of the following quantities related to a nucleus does NOT change?
A. Mass
B. Volume
C. Density
D. Binding energy
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#14 Class 12 Physics Atoms 2023 Long 5M CBSE
Write the three postulates of Bohr's model of the hydrogen atom. Show that, in this model, the frequency of revolution of an electron in its $n$th orbit is proportional to $(1/n^3)$.
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#15 Class 12 Physics Atoms 2021 Mcq 1M CBSE
In a Rutherford scattering experiment, when an $\alpha$-particle of mass $m_1$ approaches a target nucleus of charge $Ze$ and mass $m_2$, the distance of closest approach is $d_0$. The energy of the particle is
A. directly proportional to $Z$
B. inversely proportional to $Z$
C. directly proportional to $m_2$
D. directly proportional to $m_1 m_2$
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#16 Class 12 Physics Atoms 2022 Short 3M CBSE
In the spectrum of hydrogen, find the ratio of the longest wavelength in the Lyman series to the longest wavelength in the Balmer series.
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#17 Class 12 Physics Atoms 2019 Short 1M CBSE
As the number of orbit $n$ increases, what happens to the difference of energy between consecutive energy levels?
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#18 Class 12 Physics Atoms 2020 Short 1M CBSE
Find the speed of an electron in the 4th orbit of a hydrogen atom.
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#19 Class 12 Physics Atoms 2021 Short 2M CBSE
The short wavelength limit for the Lyman series of the hydrogen spectrum is 913.4 Å. Calculate the short wavelength limit for the Balmer series.
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#20 Class 12 Physics Atoms 2021 Short 3M CBSE
The total energy of an electron in the first excited state of the hydrogen atom is about $-3.4$ eV. (a) What is the kinetic energy of the electron in this state? (b) What is the potential energy of the electron in thi...
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