In a hypothetical Bohr hydrogen, the mass of the electron is doubled. The energy E0 and the radius r0 of the first orbit will be (a0 is the Bohr radius) 
(a) E0=-27.2 eV; r0=a0/2
(b) E0=-27.2 eV; r0=a0
(c) E0=-13.6 eV; r0=a0/2
(d) E0=-13.6 eV; r0=a0

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A double charged lithium atom is equivalent to hydrogen whose atomic number is 3. The wavelength of required radiation for exciting electron from first to third Bohr orbit in Li++ will be (Ionisation energy of hydrogen atom is 13.6eV) 
(a) 182.51 Å                 (b) 177.17 Å
(c) 142.25 Å                 (d) 113.74 Å

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The ionisation potential of H-atom is  13.6 V. When it is excited from ground state by monochromatic radiations of 970.6 A0, the number of emission lines will be (according to Bohr’s theory) 
(a) 10            (b) 8
(c) 6              (d) 4

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A neutron with velocity V strikes a stationary deuterium atom. Its kinetic energy changes by a factor of 
(a) 1516              (b) 12
(c) 21                (d) None of these

Concept Questions :-

Mass-energy equivalent
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The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is 1.4 kilowatt/m2.The average earth- sun distance is 1.5×1011 metres. The mass lost by the sun per day is
(1 day = 86400 seconds) 
(a) 4.4×109 kg          (b) 7.6×1014 kg
(c) 3.8×1012 kg         (d) 3.8×1014 kg

Concept Questions :-

Mass-energy equivalent
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The binding energy per nucleon of O16 is 7.97 MeV and that of O17 is 7.75 MeV. The energy (in MeV) required to remove a neutron from O17 is 
(a) 3.52                 (b) 3.64
(c) 4.23                 (d) 7.86

Concept Questions :-

Nuclear binding energy
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The rest energy of an electron is 0.511 MeV. The electron is accelerated from rest to a velocity 0.5 c. The change in its energy will be
(a) 0.026 MeV            (b) 0.051 MeV
(c) 0.079 MeV            (d) 0.105 MeV

Concept Questions :-

Mass-energy equivalent
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For uranium nucleus how does its mass vary with volume

(a) mV           (b) m1/V
(c)  mV       (d) mV2

Concept Questions :-

Radioactivity
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The rest mass of an electron as well as that of positron is 0.51 MeV. When an electron and positron are annihilated, they produce gamma-rays of wavelength(s)-

(a) 0.012 Å               (b) 0.024 Å
(c) 0.012 Å to       (d) 0.024 Å to 

Concept Questions :-

Mass-energy equivalent
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In the nuclear fusion reaction H12+H13He24+n given that the repulsive potential energy between the two nuclei is -7.7×10-14 J, the temperature at which the gases must be heated to initiate the reaction is nearly
[Boltzmann’s constant k=1.38×10-23 J/K)
(a)109 K            (b) 107 K
(c) 105 K           (d)  103 K

Concept Questions :-

Mass-energy equivalent
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