The Bohr model for the spectra of a \(H\)-atom:
(a) | will not apply to hydrogen in the molecular form. |
(b) | will not be applicable as it is for a \(He\)-atom. |
(c) | is valid only at room temperature. |
(d) | predicts continuous as well as discrete spectral lines. |
1. | (a), (b) | 2. | (c), (d) |
3. | (b), (c) | 4. | (a), (d) |
An ionised \(\text H\)-molecule consists of an electron and two protons. The protons are separated by a small distance of the order of angstrom. In the ground state:
(a) | the electron would not move in circular orbits. |
(b) | the energy would be \(2^{4}\) times that of a \(\text H\)-atom. |
(c) | the electron's orbit would go around the protons. |
(d) | the molecule will soon decay in a proton and a \(\text H\)-atom. |
1. | (a), (b) | 2. | (a), (c) |
3. | (b), (c), (d) | 4. | (c), (d) |
The total energy of an electron in the \(n^{th}\) stationary orbit of the hydrogen atom can be obtained by:
1. \(E_n = \frac{13.6}{n^2}~\text{eV}\)
2. \(E_n = -\frac{13.6}{n^2}~\text{eV}\)
3. \(E_n = \frac{1.36}{n^2}~\text{eV}\)
4. \(E_n = -{13.6}\times{n^2}~\text{eV}\)
The transition from the state \(n=3\) to \(n=1\) in hydrogen-like atoms results in ultraviolet radiation. Infrared radiation will be obtained in the transition from:
1. \(3\rightarrow 2\)
2. \(4\rightarrow 2\)
3. \(4\rightarrow 3\)
4. \(2\rightarrow 1\)
1. | the first line of the Lyman series. |
2. | the second line of the Balmer series. |
3. | the first line of the Paschen series. |
4. | the second line of the Paschen series. |
1. | \(0.53 \times 10^{-13} ~\text{m},-3.6 ~\text{eV}\) |
2. | \(25.6 \times 10^{-13} ~\text{m},-2.8 ~\text{eV}\) |
3. | \(2.56 \times 10^{-13} ~\text{m},-2.8 ~\text{keV}\) |
4. | \(2.56 \times 10^{-13} ~\text{m},-13.6 ~\text{eV}\) |
What is the shortest wavelength present in the Paschen series of spectral lines?
1. \(818.9~\text{nm}\)
2. \(779~\text{nm}\)
3. \(500~\text{nm}\)
4. \(1024~\text{nm}\)
Atomic number of H-like atom with ionization potential \(122.4~\text{V}\) for \(n=1\) is:
1. \(1\)
2. \(2\)
3. \(3\)
4. \(4\)
It is found experimentally that \(13.6~\text{eV}\) energy is required to separate a hydrogen atom into a proton and an electron. The velocity of the electron in a hydrogen atom is:
1. \(3.2\times10^6~\text{m/s}\)
2. \(2.2\times10^6~\text{m/s}\)
3. \(3.2\times10^6~\text{m/s}\)
4. \(1.2\times10^6~\text{m/s}\)
For which one of the following Bohr models is not valid?
1. | Singly ionised helium atom \(\big(\mathrm{He}^{+}\big).\) |
2. | Deuteron atom. |
3. | Singly ionised neon atom \(\big(\mathrm{Ne}^{+}\big).\) |
4. | Hydrogen atom. |