Q. No.What is the ratio of the circumference of the first Bohr orbit for the electron in the hydrogen atom to the de-Broglie wavelength of electrons having the same velocity as the electron in the first Bohr orbit of the hydrogen atom?
1. \(1:1\)
2. \(1:2\)
3. \(1:4\)
4. \(2:1\)
In \(1911\), the physician Ernest Rutherford discovered that atoms have a tiny, dense nucleus by shooting positively charged particles at a very thin gold foil. A key physical property that led Rutherford to use gold was that it was:
1. electrically conducting
2. highly malleable
3. shiny
4. non-reactive
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. |
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 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 |
| 1. | total energy of electron in \(1\text{st}\) orbit of \(\mathrm{He}^{+}\) |
| 2. | total energy of electron in \(3\text{rd}\) orbit of \(\mathrm{He}^{+}\) |
| 3. | total energy of electron in \(2\text{nd}\) orbit of \(\mathrm{Li}^{++}\) |
| 4. | total energy of electron in \(3\text{rd}\) orbit of \(\mathrm{Li}^{++}\) |
An electron revolves around a nucleus of charge \(Ze\). In order to excite the electron from the state \(n=3\) to \(n=4\), the energy required is \(66.0 ~\text{eV}\).
The value of \(Z\) will be:
1. \(25\)
2. \(10\)
3. \(4\)
4. \(5\)
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. | \(\dfrac{1}{47}\) |
1. \(f_1-f_2=f_3\)
2. \(f_2-f_1=f_3\)
3. \(f_1+f_2=f_3\)
4. \(2f_1 = f_2 + f_3\)
| 1. | \(5\rightarrow 4\) | 2. | \(3\rightarrow 2\) |
| 3. | \(2\rightarrow 1\) | 4. | \(3\rightarrow 1\) |
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