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Q. No.Whenever a photon is emitted by a hydrogen atom in the Paschen series, it is followed by further emissions of photons, in the Balmer series or the Lyman series.
These photons can have:
1.
2 possible energy values.
2.
3 possible energy values.
3.
4 possible energy values.
4.
5 possible energy values.
Subtopic: Spectral Series |
65%
Level 2: 60%+
Hints
Given below are two statements:
| Assertion (A): | The magnetic moment of a hydrogen-like atom is higher when it is in a state of higher quantum number \(n.\) |
| Reason (R): | The magnetic moment of hydrogen-like atom, as calculated from Bohr's theory, is directly proportional to the principal quantum number \(n.\) |
| 1. | (A) is True but (R) is False. |
| 2. | (A) is False but (R) is True. |
| 3. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 4. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
Subtopic: Bohr's Model of Atom |
77%
Level 2: 60%+
Hints
An electron of mass \(m\) (charge \(e\)) moves in a circular orbit in a uniform magnetic field. Assume that Bohr's law of quantisation of angular momentum is valid for the electron. The minimum possible magnetic flux (flux of magnetic field) through the electron's orbit is:
| 1. | \(\dfrac he\) | 2. | \(\dfrac h{2e}\) |
| 3. | \(\dfrac {2h}e\) | 4. | \(\dfrac h{2\pi e}\) |
Subtopic: Bohr's Model of Atom |
56%
Level 3: 35%-60%
Hints
Electrons accelerated through a potential difference \(V_0\) are incident on a gas of hydrogen atoms in the ground state. For what minimum value of \(V_0\) will the collisions of the electrons with the atom be perfectly inelastic?
1. \(13.6\) V
2. \(27.2\) V
3. \(10.2\) V
4. \(6.8\) V
1. \(13.6\) V
2. \(27.2\) V
3. \(10.2\) V
4. \(6.8\) V
Subtopic: Bohr's Model of Atom |
Level 4: Below 35%
Hints
An electron in an \(\mathrm{H}\text-\)atom makes a transition from the ground state into another state where its de-Broglie wavelength is doubled. The energy required to make this transition is:
1. \(13.6~\text{eV}\)
2. \(10.2~\text{eV}\)
3. \(12.75~\text{eV}\)
4. \(12.1~\text{eV}\)
1. \(13.6~\text{eV}\)
2. \(10.2~\text{eV}\)
3. \(12.75~\text{eV}\)
4. \(12.1~\text{eV}\)
Subtopic: Bohr's Model of Atom |
71%
Level 2: 60%+
Hints
The de-Broglie wavelength of an electron in the ground state of the \(\mathrm{H\text-}\)atoms is \(\lambda_1,\) while that in the \(\mathrm{He}^+\) ion is \(\lambda_2.\) The ratio \(\dfrac{\lambda_1}{\lambda_2}\) is:
| 1. | \(4\) | 2. | \(2\) |
| 3. | \(\dfrac12\) | 4. | \(\dfrac14\) |
Subtopic: Bohr's Model of Atom |
Level 3: 35%-60%
Hints
Light having the wavelength equal to the first line of the Lyman series is incident on a metal having a work function of \(6\) eV. The energy of the fastest photo-electron emitted is:
| 1. | \(7.6\) eV | 2. | \(4.2\) eV |
| 3. | \(2.1\) eV | 4. | \(0.8\) eV |
Subtopic: Spectral Series |
65%
Level 2: 60%+
Hints
What is the minimum voltage required to be applied to a Coolidge tube to generate \(X\)-rays of wavelength \(0.5~\mathring{A}?\) \((h=12.4~\text{keV-}\mathring{A}/c)\)
1. \(12.4\) kV
2. \(6.2\) kV
3. \(24.8\) kV
4. \(37.2\) kV
1. \(12.4\) kV
2. \(6.2\) kV
3. \(24.8\) kV
4. \(37.2\) kV
64%
Level 2: 60%+
Hints
Given below are two statements:
| Statement I: | The time period of revolution of an electron in its \(n^\mathrm{th}\) Bohr orbit in an atom is directly proportional to \(n^3.\) |
| Statement II: | The kinetic energy of an electron in its \(n^\mathrm{th}\) Bohr orbit in an atom is directly proportional to \(n.\) |
| 1. | Statement I is incorrect and Statement II is correct. |
| 2. | Both Statement I and Statement II are correct. |
| 3. | Both Statement I and Statement II are incorrect. |
| 4. | Statement I is correct and Statement II is incorrect. |
Subtopic: Bohr's Model of Atom |
81%
Level 1: 80%+
Hints
The product of the angular momentum and the kinetic energy of an electron in the \(n^\text{th}\) Bohr orbit in a hydrogen atom is proportional to:
| 1. | \(n\) | 2. | \(n^2\) |
| 3. | \(\dfrac1n\) | 4. | \(\dfrac{1}{n^3}\) |
Subtopic: Bohr's Model of Atom |
76%
Level 2: 60%+
Hints
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