JEE Questions for Physics Atoms And Nuclei Quiz 3 - MCQExams.com

Activity of a radioactive sample decreases to (1/3)rd of its original value in 3 days. Then, in 9 days its activity will become
  • (1/of the original value
  • (1/of the original value
  • (1/of the original value
  • (1/of the original value
A radioactive element forms its own isotope after 3 consecutive disintegrations. The particles emitted are
  • 3 β–particles
  • 2 β–particles and 1α–particles
  • 2 β–particles and 1 γ–particles
  • 2 α–particles and 1 β–particle
A radioactive substance has half-life of 60 min. During 3 h, the fraction of the substance that has to be decayed, will be
  • 87.5 %
  • 52.5%
  • 25.5%
  • 8.5%
The rad is the correct unit used to report the measurement of
  • the ability of a beam of γ - ray photons to produce ions in a target
  • the energy delivered by radiation to a target
  • the biological effect of radiation
  • the rate of decay of a radioactive source
A count rate metre shows a count of 240 per minute from a given radioactive source later the metre shows a count rate of 30 min-1. The half - life of the source is
  • 80 min
  • 120 min
  • 20 min
  • 30 min
The counting rate observed from a radioactive source at t = 9s was 1600 count s-1 and at t = 8s it was 100 count s-1. The counting rate observed as counts per second at t = 6s, will be
  • 400
  • 300
  • 250
  • 200
  • 150
Which of the following particles do not exist in the 92U238
  • 92 protons
  • 92 electrons
  • 146 neutrons
  • None of these
A nucleus of mass M + ∆m is at rest and decays into two daughter nuclei of equal mass (M/each. Speed of light is c.
The binding energy per nucleon for the parent nucleus is E1 and that for the daughter nuclei is E2. Then,
  • E2 = 2E1
  • E1 > E2
  • E2 > E1
  • E1 = 2E2
The energy equivalent to 1 mg of matter in MeV is
  • 56.25 × 1022
  • 56.25× 1024
  • 5.625 × 1023
  • 56.25 × 1028

Physics-Atoms and Nuclei-62471.png
  • 3 : 58
  • 58 : 3
  • 1 : 58
  • 58 : 1
Fusion reaction takes place at high temperature because
  • KE is high enough to overcome repulsion between nuclei
  • nuclei are most stable at this temperature
  • nuclei are unstable at this temperature
  • None of the above
Sun maintains its shining because of the
  • fission of helium
  • chemical reaction
  • fusion of hydrogen nuclei
  • burning of carbon
Half life of radium is 1600 years. Its average life is
  • 3200 years
  • 4800 years
  • 2309 years
  • 4217 years
A radioactive element X converts into another stable element Y. Half life of x is 2 hrs. Initially, only X is present. After time t, the ratio of atoms of X and Y is found to be 1 : 4. Then t in hours is
  • 2
  • 4
  • 6
  • between 4 and 6
In Rutherford experiment, a 5.3 MeV a – particle moves towards the gold nucleus (Z = 79). How close does the alpha particle to get the centre of the nucleus, before it comes momentarily to rest and reverses its motion?
(ϵ0 = 8.8 × 10-12 F/m)
  • 3.4 × 10-15 m
  • 8.6 × 10-14 m
  • 4.3 × 10-14 m
  • 1.6 × 10-14 m
Rutherford's atomic model could account for
  • concept of stationary orbits
  • the positively charged control core of an atom
  • origin of spectra
  • stability of atoms
Assuming the mass of earth as, 6.64 × 1024 kg and the average mass of the atoms that makes up earth as 40 u (atomic mass unit), the number of atoms in the earth is approximately
  • 1030
  • 1040
  • 1050
  • 1060
Radius of 2He4 nucleus is 3 Fm. The radius of 82Pb206 nucleus will be
  • 5 Fm
  • 6 Fm
  • 11.16 Fm
  • 8 Fm
Number of neutrons in C12 and C14 are
  • 8 and 6
  • 6 and 8
  • 6 and 6
  • 8 and 8
An a nucleus of energy 1/2 mv2 bombards a heavy nuclear target of charge Ze. Then, the distance of closest approach for the alpha nucleus will be proportional to
  • v2
  • 1/m
  • 1/v4
  • 1/Ze
Hydrogen (1H1), deuterium (1H2), singly ionised helium (2He4)+ and doubly ionised lithium (3Li8)++ all have one electron around the nucleus. Consider an electron transition from n = 2 ton =1. If the wavelengths of emitted are λ1, λ2, λ3, ans λ4, respectively for four elements, then approximately which one of the following is correct?
  • 4λ1 = 2λ2 = 2λ3 = λ4
  • λ1 = 2λ2 = 2λ3 = λ4
  • λ1 = λ2 = 4λ3 = 9λ4
  • λ1 = 2λ2 = 3λ3 = 4λ4
A proton and an α–particle, accelerated through the same potential difference, enter a region of uniform magnetic field normally. If the radius of the proton orbit is 10 cm, then radius of α–particle is
  • 10 cm
  • 10√2 cm
  • 20 cm
  • 5√2 cm
Which of the following spectral series of hydrogen atom is lying in visible range of electromagnetic wave?
  • Paschen series
  • Pfund series
  • Lyman series
  • Balmer series
What is the energy of the electron revolving in third orbit expressed in eV'?
  • 1.51 ev
  • 3.4 ev
  • 4.53 ev
  • 4 ev
The radius of the first orbit of hydrogen is rH, and the energy in the ground state is –13.6 eV. Considering a μ- -particle with a mass 207 me revolving round a proton as in hydrogen atom, the energy and radius of proton and μ- -combination respectively in the first orbit are (assume nucleus to be stationary).

  • Physics-Atoms and Nuclei-62478.png
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    Physics-Atoms and Nuclei-62479.png

  • Physics-Atoms and Nuclei-62480.png

  • Physics-Atoms and Nuclei-62481.png
If the radius of a nucleus with mass number 125 is 1.5 Fm, then radius of a nucleus with mass number 64 is
  • 0.48 Fm
  • 0.96 Fm
  • 1.92 Fm
  • 1.2 Fm
The ratio of radii of nuclei of two atoms of element of atomic mass numbers 27 and 64 is
  • 3 : 4
  • 4 : 3
  • 9 : 16
  • 16 : 9
The value of Rydberg constant is
  • 1.997 × 107 m-1
  • 1.097 × 10-7 m-1
  • 1.097× 107 m-1
  • 19.97 × 107 m-1
The total energy of an electron in 4th orbit of hydrogen atom is
  • –13.6 eV
  • –3.4 eV
  • –1.51 eV
  • –0.85 eV
The radius of the orbit of an electron in a hydrogen like atom is 4.5 ao, where ao is the Bohr radius. Its orbital angular momentum is 3h/2π. It is given that h is Planck's constant and R is Rydberg's constant. The possible wavelength (λ), when the atom de - excites, is (are)
  • 9/32R
  • 9/16R
  • 9/5R
  • 4?3R
If R is the Rydberg's constant for hydrogen the wave number of the first line in the Lyman series will be
  • R/4
  • 3R/4
  • R/2
  • 2R
What is de-Broglie wavelength of electron having energy 10 keV?

  • Physics-Atoms and Nuclei-62486.png
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    Physics-Atoms and Nuclei-62487.png

  • Physics-Atoms and Nuclei-62488.png

  • Physics-Atoms and Nuclei-62489.png
A proton is fired from very far away towards a nucleus with charge Q = 120 e, where e is the electronic charge. It makes a closest approach of 10 fm to the nucleus. The de-Broglie wavelength (in units of Fm) of the proton at its start is [take, the proton mass, mP = (5/× 10-27 kg,
h/e = 4.2 × 10-15 Js/C,
(1/4πϵo) = 9 × 109 m/F, 1 Fm = 10-15 m]
  • 7 Fm
  • 8 Fm
  • 10 Fm
  • 2 Fm
Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then, the number of spectral lines in the emission spectra will be
  • 2
  • 3
  • 5
  • 6
The wavelength of the first spectral line in the Balmer series of hydrogen atoms is 6561Å. The wavelength of the second spectral line in Balmer series of singly ionised helium atom is

  • Physics-Atoms and Nuclei-62494.png
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    Physics-Atoms and Nuclei-62495.png

  • Physics-Atoms and Nuclei-62496.png

  • Physics-Atoms and Nuclei-62497.png
Energy required for the electron excitation in Li2+ from the first to the third Bohr orbit is
  • 36.3 eV
  • 108.8 eV
  • 122.4 eV
  • 12.1 eV
When an electron jumps from the orbit a = 2 to n = 4, then wavelength of the radiations absorbed will be (R is Rydberg's constant)
  • 3R/16
  • 5R/16
  • 16/5R
  • 16/3R
The ratio of minimum wavelength of Lyman and Balmer series will be
  • 10
  • 5
  • 0.25
  • 1.25
In an inelastic collision, an electron excites a hydrogen atom from its ground state to a M–shell state. A second electron collides instantaneously with the excited hydrogen atom in the M–state and ionises it. At least how much energy the second electron transfers to the atom in the M-state?
  • + 3.4 eV
  • + 1.5 eV
  • – 3.4 eV
  • – 1.51 eV
According to the Bohr's atomic model, the relation between principal quantum number (n) and radius of orbit (r) is
  • r ∝ n2
  • r ∝ 1/n2
  • r ∝ 1/n
  • r ∝ n
The acceleration of electron in the first orbit of hydrogen atom is

  • Physics-Atoms and Nuclei-62502.png
  • 2)
    Physics-Atoms and Nuclei-62503.png

  • Physics-Atoms and Nuclei-62504.png

  • Physics-Atoms and Nuclei-62505.png
An electron collides with a hydrogen atom in its ground state and excites it to n = 3. The energy given to hydrogen atom in this inelastic collision is (neglect the recoiling of hydrogen atom)
  • 10.2 eV
  • 12.1 eV
  • 12.5 eV
  • None of these
An electron of charge e moves with a constant speed v along a circle of radius r, its magnetic moment will be
  • evr
  • evr/2
  • πr2 ev
  • 2πrev
An electron is moving in an orbit of a hydrogen atom from which there can be a maximum of six transition. An electron is moving in an orbit of another hydrogen atom from which there can be a maximum of three transition. The ratio of the velocities of the electron in these two orbits is
  • 1/2
  • 2/1
  • 5/4
  • 3/4
v1 is the frequency of the series limit of Lyman series, v2 is the frequency of the first line of Lyman series and v3 is the frequency of the series limit of the Balmer series. Then,
  • v1 – v2 = v3
  • v1 = v2 - v3

  • Physics-Atoms and Nuclei-62506.png

  • Physics-Atoms and Nuclei-62507.png
The spectrum of an oil flame is an example for
  • line emission spectrum
  • continuous emission spectrum
  • line absorption spectrum
  • band emission spectrum
Two energy levels of an electron in an atom are separated by 2.3 eV. The frequency of radiation emitted when the electrons go from higher to lower level is
  • 6.95 × 1014 Hz
  • 3.68 × 1015 Hz
  • 5.5 × 1014 Hz
  • 9.11 × 1015 Hz
Of the following transitions in the hydrogen atom, the one which gives an emission line of the highest frequency is
  • n = 1 to n = 2
  • n = 2 to n = 1
  • n = 3 to n = 10
  • n = 10 to n = 3
For an electron in the second orbit of Bohr's hydrogen atom, the moment of linear momentum is
  • nπ
  • 2πh
  • 2h/π
  • h/π
The wavelength of radiation emitted is λ0 when an electron jumps from the third to the second orbit of hydrogen atom. For the electron jump from the fourth to the second orbit of hydrogen atom, the wavelength of radiation emitted will be

  • Physics-Atoms and Nuclei-62509.png
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    Physics-Atoms and Nuclei-62510.png

  • Physics-Atoms and Nuclei-62511.png

  • Physics-Atoms and Nuclei-62512.png
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