JEE Questions for Physics Atoms And Nuclei Quiz 2 - MCQExams.com

Excitation energy of a hydrogen like atom in its first excitation state is 40.8 eV. Energy needed to remove the electron from the ion in ground state is
  • 40.8eV
  • 27.2 eV
  • 54.4eV
  • 13.6eV
Mercury vapour lamp gives
  • continuous spectrum
  • line spectrum
  • band spectrum
  • absorption spectrum
Electrons in the atom are held to the nucleus by
  • Coulomb's forces
  • nuclear forces
  • van der Waals' forces
  • gravitational forces
In hydrogen atom, the electron is moving round the nucleus 2.18 × 106 ms-1 in an orbit of radius 0.528 Å. The acceleration of the electron is
  • 9 × 1018 ms-2
  • 9 × 1022 ms-2
  • 9 × 10-22 ms-2
  • 9 × 1012 ms-2
The ionisation energy of 10 times ionised sodium atom is

  • Physics-Atoms and Nuclei-62433.png
  • 2)
    Physics-Atoms and Nuclei-62434.png

  • Physics-Atoms and Nuclei-62435.png

  • Physics-Atoms and Nuclei-62436.png

Physics-Atoms and Nuclei-62438.png
  • 1.5 eV
  • 0.85 eV
  • 3.4 eV
  • 1.9 eV
Bohr's atom model assumes
  • the nucleus is of infinite mass and is at rest
  • electrons in a quantised orbit will not radiate energy
  • mass of electron remains constant
  • All the above conditions
Wavelength of first line in Lyman series is λ. The wavelength of first line in Balmer series is

  • Physics-Atoms and Nuclei-62439.png
  • 2)
    Physics-Atoms and Nuclei-62440.png

  • Physics-Atoms and Nuclei-62441.png

  • Physics-Atoms and Nuclei-62442.png
A narrow beam of protons and deuterons, each having the same momentum, enters a region of uniform magnetic field directed perpendicular to their direction of momentum. The ratio of the radii of the circular paths described by them is
  • 1 : 2
  • 1 : 1
  • 2 : 1
  • 1 : 3
A neutron is moving with velocity u. It collides head on and elastically with an atom of mass number A. If the initial kinetic energy of the neutron is E, then how much kinetic energy will be retained by the neutron after reflection?

  • Physics-Atoms and Nuclei-62444.png
  • 2)
    Physics-Atoms and Nuclei-62445.png

  • Physics-Atoms and Nuclei-62446.png

  • Physics-Atoms and Nuclei-62447.png
Nucleus of mass number A, originally at rest, emits the α-particle with speed v. The daughter nucleus recoils with a speed of
  • 2v/(A + 4)
  • 4v/(A + 4)
  • 4v/(A - 4)
  • 2v/(A - 4)
When 90Th228 transforms to 83Bi212, then the number to the emitted α and β- particles is, respectively
  • 8α, 7β
  • 4α, 7β
  • 4α, 4β
  • 4α, 1β

Physics-Atoms and Nuclei-62449.png
  • quarks
  • neutrons
  • nucleons
  • protons

Physics-Atoms and Nuclei-62450.png
  • III and IV
  • I and II
  • II and III
  • I and IV

Physics-Atoms and Nuclei-62451.png
  • proton
  • oxygen – 12
  • carbon – 12
  • nitrogen – 12
A certain radioactive material ZXA starts emitting α and β particles successively such that the end product is Z-3YA-8. The number of α and β particles emitted are
  • 4 and 5 respectively
  • 2 and 1 respectively
  • 3 and 4 respectively
  • 3 and 8 respectively
Two nuclei have their mass numbers in the ratio of 1: 3. The ratio of their nuclear densities would be
  • 1 : 3
  • 3 : 1
  • 31/3 : 1
  • 1 : 1
A photon creates a pair of electron positron with equal kinetic energy. Let kinetic energy of each particle is 0.29 MeV. Then. what should be energy of the photon?
  • 1.60 MeV
  • 1.63 MeV
  • 2.0 MeV
  • 1.90 MeV
92U235 undergoes successive disintegrations with the end product of 82Pb203. The number α and β-particles emitted are
  • α = 6, β = 4
  • α = 6, β = 0
  • α = 8, β = 6
  • α = 3, β = 3
Which of the following is a possible nuclear reaction ?

  • Physics-Atoms and Nuclei-62454.png
  • 2)
    Physics-Atoms and Nuclei-62455.png

  • Physics-Atoms and Nuclei-62456.png

  • Physics-Atoms and Nuclei-62457.png
The radius of nucleus is
  • proportional to its mass number
  • inversely proportional to its mass number
  • proportional to the cube root of its mass number
  • not related to its mass number
mp and mn are masses of proton and neutron, respectively. An element of mass M has Z protons and N neutrons then
  • M > (Zmp + Nmn)
  • M = (Zmp + Nmn)
  • M < (Zmp + Nmn)
  • M may be grater than less than or equal to Zmp + Nmn, depending on nature of element
A nucleus with Z = 92 emits the following in a sequence : α, α, β-, β-, α, α, α, α, β-, β-, α, β+, β+, α. The Z of the resulting nucleus is
  • 76
  • 78
  • 82
  • 74
A nucleus disintegrates into two nuclear parts which have their velocities in the ratio 2: 1. The ratio of their nuclear sizes will be
  • 21/3 : 1
  • 1 : 31/2
  • 31/2 : 1
  • 1 : 21/3

Physics-Atoms and Nuclei-62460.png
  • 13.9 MeV
  • 26.9 MeV
  • 23.6 MeV
  • 19.2 MeV
When 3Li7 nuclei are bombarded by protons, and the resultant nuclei are 4Be8. the emitted particles will be
  • α – particles
  • β – particles
  • γ – photons
  • neutrons
The mass number of nucleus is
  • sometimes equal to its atomic number
  • sometimes less than and sometimes more than its atomic number
  • always less than its atomic number
  • always more than its atomic number
A free neutron decays spontaneously into
  • a proton, an electron and anti-neutrino
  • a proton, an electron and aneutrino
  • a proton and electron
  • a proton, an electron, a neutrino and an anti-neutrino
A nucleus decays by β+ – emission followed by a γ – emission. If the atomic and mass numbers of the parent nucleus are Z and A respectively, the corresponding numbers for the daughter nucleus are respectively
  • Z – 1 and A – 1
  • Z + 1 and A
  • Z – 1 and A
  • Z + 1 and A – 1
If the binding energies of a deuteron and an α–particle are 1.125 MeV and 7.2 MeV, respectively, then the more stable of the two is
  • deuteron
  • α – particles
  • Both (and (2)
  • sometimes deuteron and sometimes α – particle
The particle A is converted into C via following reaction,
A → B + 2 He4
B → C + 2e-
Then,
  • A and C are isobars
  • A and C are isotopes
  • A and B are isobars
  • A and B are isotopes
The fraction of atoms of radioactive element that decays in 6 days is 7/8. The fraction that decays in 10 days will be
  • 77/80
  • 71/80
  • 31/32
  • 15/16
The binding energy per nucleon in a heavy nucleus is of the order of
  • 8 MeV
  • 7 MeV
  • 5 MeV
  • 2 MeV

Physics-Atoms and Nuclei-62462.png
  • 7.57 MeV
  • 8.36 MeV
  • 9.12 MeV
  • 9.56 MeV
1 curie represents
  • 1disintegration per second
  • 106 disintegration per second
  • 3.7 × 1010 disintegration per second
  • 3. 7 ×107 disintegration per second
The radioactivity of a sample is I1 at a time t1 and I2 at a t2. If the half - life of the sample is t1/2, then the number of nuclei that have disintegrated in the time t2 – t1 is proportional to
  • I1t2 – I2t1
  • I1 – I1

  • Physics-Atoms and Nuclei-62463.png
  • (I1 – I2)t1/2
Consider an initially pure 3.4 g sample of 67Ga, an isotope that has a half – life of 78h. What is its initial decay rate?
  • 8.00 × 106 s-1
  • 6.27 × 106 s-1
  • 7.53 × 106 s-1
  • 8.53 × 1015 s-1
80 kg of a radioactive material reduces to 10 kg in 1 h. The decay constant of the material is
  • 5.8 × 10-4 s-1
  • 1.16 × 10-3 s-1
  • 2.32 × 10-3 s-1
  • 4.64 × 10-3 s-1
A radioactive sample S1 having the activity A1 has twice the number of nuclei as another sample S2 of activity A2. If A2 = 2A1, then the ratio of half - life of S1 to the half - life of S2 is
  • 4
  • 2
  • 0.25
  • 0.75
When a neutron is disintegrated to give a β -particle,
  • a neutrino alone is emitted
  • a proton and neutrino are emitted
  • a proton alone is emitted
  • a proton and an anti-neutrino arc emitted
How many neutrons are more than protons in 92U235 nucleus?
  • 54
  • 49
  • 51
  • 143
If the decay constant of a radioactive substance is λ, then its half - life is
  • 1/λ (loge) 2
  • 1/λ
  • λ loge 2
  • λ/(loge 2)
The half-life period of a radioactive substance is 3 days. Three fourth of substance decays in
  • 3 days
  • 6 days
  • 9 days
  • 12 days
A radioactive material decays by simultaneous emission of two particles with half-lifes 1620 yr and 810 yr, respectively. The time in year after which one-fourth of the material remains, is
  • 4860 yr
  • 3240 yr
  • 2340 yr
  • 1080 yr
The proper life of point (π+) is 2.5 × 10-8 s. In a beam of pions travelling with a speed of 0.9c, the pion in the laboratory frame can travel a maximum distance of
  • 6.75 m
  • 15.49 m
  • 7.50 m
  • 17.10 m
One Becquerel is defined as
  • 1 disintegration per second
  • 106 disintegration per second
  • 3.7 × 1010 disintegration per second
  • 103 disintegration per second
During the β- decay
  • an atomic electron is ejected
  • an electron, already present within the nucleus, is ejected
  • a proton in the nucleus decays emitting an electron
  • a neutron in the nucleus decays emitting an electron
The half - life of At215 is 100 μs. If a sample contains 215 mg of At215, the activity of the sample initially is
  • 102 Bq
  • 3 × 1010 Bq
  • 4.17 × 1024 Bq
  • 1.16 × 105 Bq
The masses of two radioactive substances are same and their half-lifes are 1 yr and 2 yr respectively. The ratio of their activities after 4 yr will be
  • 1 : 4
  • 1 : 2
  • 1 : 3
  • 1 ; 6
Two radioactive substances A and B have decay constants 5λ and λ , respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be (1/e)2 after a time interval
  • 1/4λ
  • 4λ
  • 2λ
  • 1/2λ
0:0:1


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