Continuous emission spectrum is produced by

• incandescent electric lamp

• mercury vapour lamp

• sodium vapour lamp

• polyatomic substances

Hydrogen atom from excited state comes to the ground stage by emitting a photon of wavelength λ. If R is the Rydberg constant, the principal quantum number n of the excited state

• $\sqrt{\frac{\mathrm{\lambda R}}{\mathrm{\lambda R} - 1}}$

• $\sqrt{\frac{\mathrm{\lambda }}{\mathrm{\lambda R} - 1}}$

• $\sqrt{\frac{{\mathrm{\lambda R}}^2}{\mathrm{\lambda R} - 1}}$

• $\sqrt{\frac{\mathrm{\lambda R}}{\mathrm{\lambda } - 1}}$

The spectrum of an oil flame is an example for

• line emission spectrum

• continuous emission spectrum

• line absorption spectrum

• band emission spectrum

An electron is moving in an orbit of a hydrogen atom from which there can be a maximum of six transition. An electron is moving in an orbit of another hydrogen atom from which there can be a maximum of three transition. The ratio of the velocities of the electron in these two orbits is

• $\frac{1}{2}$

• $\frac{2}{1}$

• $\frac{5}{4}$

• $\frac{3}{4}$

v₁ is the frequency of the series limit of Lyman series, v₂ is the frequency of the first line of Lyman series and v₃ is the frequency of the series limit of the Balmer series. Then

• v₁ − v₂ = v₃

• v₁ = v₂ − v₃

• $\frac{1}{{\mathrm{v}}_2} = \frac{1}{{\mathrm{v}}_1} + \frac{1}{{\mathrm{v}}_3}$

• $\frac{1}{{\mathrm{v}}_1} = \frac{1}{{\mathrm{v}}_2} + \frac{1}{{\mathrm{v}}_3}$

The de-Broglie wavelength ofthe electron in the ground state of the hydrogen atom is (radius of the first orbit of hydrogen atom = 0.53 $\stackrel{\circ }{\mathrm{A}}$)

• $1.67 \stackrel{\circ }{\mathrm{A}}$

• $3.33 \stackrel{\circ }{\mathrm{A}}$

• $1.06 \stackrel{\circ }{\mathrm{A}}$

• $0.53 \stackrel{\circ }{\mathrm{A}}$

Rutherford's atomic model could account for

• stability of atoms

• origin of spectra

• the positive charged central core of an atom

• concept of stationary orbits

68.

The ratio of minimum wavelengths of Lyman and Balmer series will be

• 1.25

• 0.25

• 5

• 10

An electron of mass m_e and a proton of mass m_p are moving with the same speed. The ratio of their de-Broglie's wavelengths λ_e/ λ_p is

• 1

• 1836

• $\frac{1}{1836}$

• 918

A proton and an alpha particle are accelerated under the same potential difference. The ratio of de-Broglie wavelengths of the proton and the alpha particle is

• 2

• $\sqrt{8}$

• $\frac{1}{\sqrt{8}}$

• 1