When electron jumps from n = 4 to n = 2 orbit, we get [2000]

1. second line of Lyman series

2. second line of Balmer series

3. second line of Paschen series

4. an absorption line of Balmer series

In terms of Bohr radius $a_0$, the radius of the second Bohr orbit of a hydrogen atom is given by [1992]

1. 4$a_0$ 

2. 8$a_0$ 

3. $\sqrt{2}$$a_0$     

4. 2$a_0$

A diatomic molecule is made of two masses $m_1 and m_2$ which are separated by a distance r.  If we calculate its rotational energy by applying Bohr's rule of angular momentum quantization, its energy will be given by (n is an integer):

1. $\frac{{\left(m_1+m_2\right)}^2{n}^2{h}^2}{2m_1^2{m}_2^2{r}^2}$     

2. $\frac{n^2{h}^2}{2{\mathrm{\pi }}^2(m_1^{}+m_2^{})r^2}$

3. $\frac{2n^2{h}^2}{(m_1^{}+m_2^{})r^2}$   

4. $\frac{\left(m_1+m_2\right)n^2{h}^2}{8{\mathrm{\pi }}^2{m}_1^{}{m}_2^{}{r}^2}$

In the Bohr's hydrogen atom model, the radius of the stationary orbit is directly proportional to (n = principal quantum number) [CBSE PMT 1996; AIIMS 199; DCE 2002; AMU (med.) 2010)

1. $n^{-1}$   

2. n

3. $n^{-2}$ 

4. $n^2$

The Bohr model of the atom:

1. Assumes that the angular momentum of electrons is quantized

2. Uses Einstein's photoelectric equation

3. Predicts continuous emission spectra for atoms

4. Predicts the same emission spectra for all types of atoms

When a hydrogen atom is raised from the ground state to excited state

1. both KE and PE increase

2. both KE and PE decrease

3. PE increases and KE decreases

4. PE decreases and KE increases

A hydrogen atom is in an excited state of principal quantum number (n). It emits a photon of wavelength ($\lambda$) when it returns to the ground state. The value of n is:

1. $\sqrt{\frac{\lambda R}{\lambda R-1}}$ 

2. $\sqrt{\frac{(\lambda R-1)}{\lambda R}}$

3. $\sqrt{\lambda (R-1)}$ 

4. None of these

The ground state energy of H-atom is 13.6 eV. The energy needed to ionise H-atom from its second excited state [1991]

1. 1.51 eV

2. 3.4 eV

3. 13.6 eV

4. 12.1 eV

The given diagram indicates the energy levels of a certain atom. When the system moves from the 2E level to E, a photon of wavelength λ is emitted. What is the wavelength of the photon produced during its transition from the $\frac{4E}{3}$ level to E?

1. $\frac{\lambda }{3}$ 

2. $\frac{3\lambda }{4}$ 

3. $\frac{4\lambda }{3}$ 

4. $3\lambda$

Energy 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 [2004]

1. 1.5 eV 

2. 0.85 eV 

3. 3.4 eV 

4. 1.9 eV