The ionisation potential of H-atom is -13.6 eV. Photons with an energy of 12.85 eV are incident on a sample of H-atoms in their ground state. How many spectral lines are expected in emitted radiation?

1.  2

2.  6

3.  4

4.  1

Let f₁ be the maximum frequency of the Lyman series, f₂ be the frequency of the first line of the Lyman series, and f₃ be the frequency of the series limit of the Balmer series, then which of the following is correct?

1.  $f_1$ - $f_2$ = $f_3$

2.  $f_2$ - $f_1$ = $f_3$

3.  $f_1$ + $f_2$ = $f_3$

4.  2$f_1$ = $f_2$ + $f_3$

What happens when an electron in a hydrogen-like atom jumps from a lower energy level to a higher energy level?

If the wavelength of the first line in the Balmer Series of the hydrogen spectrum is λ, then what is the wavelength of the second line in this series?

1.  $\frac{20}{27}\lambda$

2.  $\frac{27}{20}\lambda$

3.  $\frac{25}{27}\lambda$

4.  $\frac{27}{25}\lambda$

In the Bohr model of the hydrogen atom, the force on the electron depends on the principal quantum number "n" as:

E₁, E₂ and E₃ are energies of an electron in three consecutive energy levels of a hydrogen-like atom, such that E₁<E₂<E₃. The wavelength emitted in the transition from E₃ to E₂ is λ₂ and the wavelength emitted in the transition from E₂ to E₁ is λ₁. The wavelength emitted in transition from E₃ to E₁ is:

1.  $\frac{{\lambda }_1{\lambda }_2}{{\lambda }_1-{\lambda }_2}$

2.  $\frac{{\lambda }_1+{\lambda }_2}{2}$

3.  $\sqrt{{\lambda }_1^2+{\lambda }_2^2}$

4. $\frac{{\lambda }_1{\lambda }_2}{{\lambda }_1+{\lambda }_2}$

In an atom, if the transition from n = 4 to n = 3 gives ultraviolet radiation, then to obtain infrared radiation, the transition should be:

Which other physical quantity, like angular momentum, is quantized in Bohr's model of a hydrogen atom?

1.  Kinetic energy

2.  Magnetic moment

3.  Potential energy

4.  Mechanical energy

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.

In an $\alpha$-particle scattering experiment, the number of particles scattered per minute in a direction perpendicular to the direction of incident particles is 40. What will be the number of particles scattered at an angle of 60° per minute?