The ratio of the longest to shortest wavelengths in Lyman series of hydrogen spectra is 

1. $\frac{25}{9}$

2.$\frac{17}{6}$   

3.  $\frac{9}{5}$ 

4. $\frac{4}{3}$

Hydrogen atoms are excited from ground state of the principal quantum number 4. Then, the number of spectral lines observed will be

1. 3   

2. 6

3. 5

4. 2

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$a_0$

In a hydrogen atom, which of the following electronic transitions would involve the maximum energy change?

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

Consider an electron in the \(n^\mathrm{th}\) orbit of a hydrogen atom in the Bohr model. The circumference of the orbit can be expressed in terms of the de-Broglie wavelength \(\lambda\) of that electron as:
1. \((0.529)n\lambda\)
2. \(\sqrt{n\lambda}\)
3. \((13.6)n\lambda\)
4. \(n\lambda\)

In the Bohr's model of a hydrogen atom, the centripetal force is furnished by the Coulomb attraction between the proton and the electron.  If ${\alpha }_0$ is the radius of the ground state orbit, m is the mass and e is the charge on the electron, ${\epsilon }_0$ is the vaccum permittivity, the speed of the electron is  [1998]

1. zero         

2. $\frac{e}{\sqrt{{\epsilon }_0{a}_{0}m}}$

3. $\frac{e}{\sqrt{4{\mathrm{\pi \epsilon }}_0{\mathrm{a}}_0\mathrm{m}}}$ 

4. $\frac{\sqrt{4{\mathrm{\pi \epsilon }}_0{\mathrm{a}}_0\mathrm{m}}}{e}$

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 energy of ground electronic state of hydrogen atom is -13.6 eV.  The energy of the first excited state will be [1997]

1. -54.4 eV 

2. -27.2 eV

3. -6.8 eV 

4. -3.4 eV