Which of the following curves represents the variation in the number of \(\alpha \text-\)particles scattered \((N)\) with the scattering angle \((\theta)\) in Rutherford's \(\alpha \text-\)particle scattering experiment?
| 1. | ![]() |
2. | ![]() |
| 3. | ![]() |
4. | ![]() |
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) |
| Assertion (A): | When light consisting of wavelengths corresponding to the Balmer series is incident on a gas containing \(\mathrm{He}^{+}\) ions in the first three excited states - it can be absorbed by the \(\mathrm{He}^{+}\) ions. |
| Reason (R): | All the energy levels of the \(\mathrm{He}^{+}\) ions are the same as those of the \(\mathrm{H}\) atoms. |
| 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). |
Which statement about the Rutherford model of the atom is not true?
| 1. | There is a positively charged centre in an atom called the nucleus. |
| 2. | Nearly all the mass of an atom resides in the nucleus. |
| 3. | The size of the nucleus is the same as that of the atom. |
| 4. | Electrons occupy the space surrounding the nucleus. |
Atomic number of H-like atom with ionization potential \(122.4~\text{V}\) for \(n=1\) is:
1. \(1\)
2. \(2\)
3. \(3\)
4. \(4\)
| Assertion (A): | The positively charged nucleus of an atom has a radius of almost \(10^{-15}~\text{m}\). |
| Reason (R): | In \(\alpha\)-particle scattering experiment, the distance of the closest approach for \(\alpha\)-particle is \(\approx 10^{-15}~\text m\). |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
| 1. | the radius of the electron orbit is \(r\propto\sqrt n\). |
| 2. | the speed of the electron is \(v\propto\sqrt n\). |
| 3. | the angular speed of the electron is \(\omega\propto 1/n\). |
| 4. | the angular momentum of the electron is \(\propto\sqrt n\). |
| 1. | \(-3.4~\text{eV}\) | 2. | \(-6.8~\text{eV}\) |
| 3. | \(-10.2~\text{eV}\) | 4. | \(-13.6~\text{eV}\) |
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. \(1.2\times10^6~\text{m/s}\)