An electron is moving around the nucleus of a hydrogen atom in a circular orbit of radius r. What is the coulomb force between the two? \(\left ( \text{where},K=\frac{1}{4\pi \epsilon _{0}} \right )\)
1.
2.
3.
4.
If the energy of the hydrogen atom in orbit is , then the energy in orbit of the singly ionised helium atom will be:
1. 4
2. /4
3. 2
4. /2
In which of the following systems will the radius of the first orbit (n = 1) be minimum:
1. doubly ionized lithium
2. singly ionized helium
3. deuterium atom
4. hydrogen atom
The Bohr model of atoms:
1. | uses Einstein's photoelectric equation |
2. | predicts continuous emission spectra for atoms |
3. | predicts the same emission spectra for all types of atoms |
4. | assumes that the angular momentum of electrons is quantized |
Energy \(\mathrm{E}\) of a hydrogen atom with principal quantum number \(n\) is given by \(E=-\frac{13.6}{n^{2}}~eV.\) The energy of a photon ejected when the electron jumps from \(n=3\) state to \(n=2\) state of hydrogen is approximately:
1. \(0.85~\mathrm{eV}\)
2. \(3.4~\mathrm{eV}\)
3. \(1.9~\mathrm{eV}\)
4. \(1.5~\mathrm{eV}\)
When an electron transitions from n = 4 to n = 2, then the emitted line in the spectrum will be:
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. |
The life span of atomic hydrogen is:
1. Fraction of one sec
2. One year
3. One hour
4. One day
In the Bohr model of H-atom, an electron (e) is revolving around a proton (p) with velocity v. If r is the radius of the orbit, m is the mass and is vacuum permittivity, then the value of v is:
1.
2.
3.
4.
Energy levels A, B and C of a certain atom correspond to increasing values of energy i.e. \(E_A<E_B<E_C\). If \(\lambda_1, ~\lambda_2\) and \(\lambda_3\) are wavelengths of radiations corresponding to transitions C to B, B to A and C to A respectively, which of the following relations is correct?
1. \(\lambda_3=\lambda_1+\lambda_2\)
2. \(\lambda_1+\lambda_2+\lambda_3=0\)
3. \(\lambda_3^2=\lambda_1^2+\lambda_2^2\)
4. \(\lambda_3=\frac{\lambda_1 \lambda_2}{\lambda_1+\lambda_2}\)
The total energy of an electron in the first excited state of a hydrogen atom is about –3.4 eV. Its kinetic energy in this state will be:
1. –6.8 eV
2. 3.4 eV
3. 6.8 eV
4. –3.4 eV