Orbital acceleration of electrons is:
1. \(\frac{n^2h^2}{4\pi^2m^2r^3}\)
2. \(\frac{n^2h^2}{4n^2r^3}\)
3. \(\frac{4n^2h^2}{\pi^2m^2r^3}\)
4. \(\frac{4n^2h^2}{4\pi^2m^2r^3}\)

Subtopic:  Bohr's Model of Atom |
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Consider the spectral line resulting from transition \(n=2\) to \(n = 1\) in the atoms and ions given below.  The shortest wavelength is given by:

1. hydrogen atom
2. deuterium
3. singly ionised helium
4. doubly ionised lithium
Subtopic:  Spectral Series |
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An α-particle of energy 5 MeV is scattered through 180° by a fixed uranium nucleus. The distance of closest approach is of the order

1. 10-10 m 

2. 10-13 m 

3. 10-14 m 

4. 10-16 m

Subtopic:  Various Atomic Models |
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Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model:

1. 13.6 eV

2. 0.65 eV

3. 1.9 eV

4. 11.1 eV

Subtopic:  Bohr's Model of Atom |
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The energy of an electron in an excited hydrogen atom is \(-3.4~\text{eV}\).  Its angular momentum will be:
(\(h = 6.626\times 10^{-34}\) J-s)
1. \(1.11\times 10^{34}~\text{J-s}\)
2. \(1.51\times 10^{-31}~\text{J-s}\)
3. \(2.11\times 10^{-34}~\text{J-s}\)
4. \(3.72\times 10^{-34}~\text{J-s}\)

Subtopic:  Bohr's Model of Atom |
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As per the Bohr model, the minimum energy (in eV) required to remove the electron from the ground state of a double ionised lithium ion (\(Z=3\)) is:
1. \(1.51\)
2. \(13.6\)
3. \(40.8\)
4. \(122.4\)

Subtopic:  Bohr's Model of Atom |
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The wavelength of Ka X-rays produced by an X-ray tube is 0.76 A. Find the atomic number of the anode material of the tube?

1. 41

2. 30

3. 20

4. 10

Subtopic:  X-Ray (OLD NCERT) |
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According to Bohr's theory, the moment of momentum of an electron revolving in second orbit of hydrogen atom will be:
1. \(2\pi h\)
2. \(\pi h\) 
3. \(\frac{h}{\pi}\)
4. \(\frac{2h}{\pi}\)

Subtopic:  Bohr's Model of Atom |
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The ionisation energy of a hydrogen atom is \(13.6~\text{eV}\). Following Bohr's theory, what is the energy corresponding to a transition between the \(3^{th}\) and \(4^{th}\) orbit?
1. \(3.40~\text{eV}\)
2. \(1.51~\text{eV}\)
3. \(0.85~\text{eV}\)
4. \(0.66~\text{eV}\)

Subtopic:  Bohr's Model of Atom |
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The ratio of the energies of the hydrogen atom in its first to second excited states is

1. 14 

2. 49

3. 94

4. 4

Subtopic:  Bohr's Model of Atom |
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