In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of:

(1) excitation of electrons in the atoms 

(2) the collision between the atoms of the gas 

(3) the collisions between the charged particles emitted from the cathode and the atoms of the gas 

(4) the collision between different electrons of the atoms of the gas 

Subtopic:  X-Ray (OLD NCERT) |
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The ratio of momenta of an electron and an \(\alpha \text-\)particle which are accelerated from rest by a potential difference of \(100~\text{V}\) is:
1. \(1\)
2. \(\sqrt{\frac{2m_e}{m_{\alpha}}}\)
3. \(\sqrt{\frac{m_e}{m_{\alpha}}}\)
4. \(\sqrt{\frac{m_e}{2m_{\alpha}}}\)

Subtopic:  Various Atomic Models |
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The fact that electric charges are integral multiples of the fundamental electronic charge was proved experimentally by 
(1) Planck                   

(2) J.J. Thomson

(3) Einstein                 

(4) Millikan

Subtopic:  Various Atomic Models |
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The specific charge of an electron is 

(a) 1.6×10-19 coulomb

(b) 4.8×10-10 stat coulomb

(c) 1.76×1011 coulomb/kg

(d) 1.76×10-11  coulomb/kg

Subtopic:  Various Atomic Models |
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The ratio of specific charge of an α-particle to that of a proton is 
(1) 2 : 1                     

(2) 1 : 1

(3) 1 : 2                     

(4) 1 : 3

Subtopic:  Various Atomic Models |
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Which of the following have the highest specific charge

(1) Positron                   

(2) Proton

(3) He++                          

(4) None of these

Subtopic:  Various Atomic Models |
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For the Bohr's first orbit of circumference 2πr, the de-Broglie wavelength of revolving electron will be

(a) 2πr                       (b) πr
(c) 12πr                      (d) 14πr

Subtopic:  Bohr's Model of Atom |
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According to de-Broglie, the de-Broglie wavelength for electron in an orbit of hydrogen atom is 10-10 m. The principle quantum number for this electron is r=5.13×10-11m
(a) 1           (b) 2
(c) 3           (d) 4

Subtopic:  Bohr's Model of Atom |
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The energy of a photon of light with wavelength 5000 Å is approximately 2.5 eV. This way the energy of an X-ray photon with wavelength 1Å would be 
(1) 2.5/5000 eV             

(2) 2.5/50002 eV

(3) 2.5×5000 eV           

(4)  2.5×50002 eV

Subtopic:  X-Ray (OLD NCERT) |
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The graph that correctly represents the relation of frequency v of a particular characteristic X-ray with the atomic number Z of the material is

Subtopic:  X-Ray (OLD NCERT) |
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