Q. No.Let \(R\) represent the orbital radius of an electron moving in an orbit and \(K\) represent its kinetic energy. Then the quantity \(KR\) varies with principal quantum number \(n\) as:
1.
2.
3.
4.
The de-Broglie wavelength of an electron in the second orbit of a hydrogen atom is equal to:
| 1. | The perimeter of the orbit. |
| 2. | The half of the perimeter of the orbit. |
| 3. | The half of the diameter of the orbit. |
| 4. | The diameter of the orbit. |
| 1. | \(5\rightarrow 4\) | 2. | \(3\rightarrow 2\) |
| 3. | \(2\rightarrow 1\) | 4. | \(3\rightarrow 1\) |
1. \(f_1-f_2=f_3\)
2. \(f_2-f_1=f_3\)
3. \(f_1+f_2=f_3\)
4. \(2f_1 = f_2 + f_3\)
What is the ratio of the speed of an electron in the first orbit of an \(\mathrm{H}\text-\)atom to the speed of light?
| 1. | \(\dfrac{1}{137}\) | 2. | \(137\) |
| 3. | \(\dfrac{1}{83}\) | 4. | \(\dfrac{1}{47}\) |
What happens when an electron makes a transition from an excited state to the ground state of a hydrogen-like atom or ion?
| 1. | Its kinetic energy increases but potential energy and total energy decrease. |
| 2. | Kinetic energy, potential energy and total energy decrease. |
| 3. | Kinetic energy decreases, potential energy increases but the total energy remains the same. |
| 4. | Kinetic energy and total energy decrease but potential energy increases. |
The wavelength of the first line of the Lyman series for a hydrogen atom is equal to that of the second line of the Balmer series for a hydrogen-like ion. What is the atomic number \(Z\) of hydrogen-like ions?
1. \(4\)
2. \(1\)
3. \(2\)
4. \(3\)
The ionisation potential of the hydrogen atom is \(13.6~\text{eV}.\) The hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy of \(12.1~\text{eV}.\) According to Bohr’s theory, the spectral lines emitted by hydrogen atoms will be:
1. two
2. three
3. four
4. one
The Rutherford \(α -\)particle experiment shows that most of the \(α -\)particles pass through almost unscattered while some are scattered through large angles. What information does it give about the structure of the atom?
| 1. | The atom is hollow. |
| 2. | The whole mass of the atom is concentrated in a small center called the nucleus. |
| 3. | The nucleus is positively charged. |
| 4. | All of the above |
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. |
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