An α-particle of energy 5 MeV is scattered through 180o by a fixed uranium nucleus. The distance of the closest approach is of the order of
1 Å
10-10 cm
10-12 cm
10-15 cm
In the Bohr model of the hydrogen atom, let R, V and E represent the radius of the orbit, the speed of electron and the total energy of the electron respectively.Which of the following quantity is proportional to the quantum number n?
E/V
R/E
VR
RE
Hydrogen atom emits blue light when it changes from n = 4 energy level to n = 2 level. Which colour of light would the atom emit when it changes from n = 5 level to n = 2 level?
red
yellow
violet
green
In terms of Bohr radius a0, the radius of the second Bohr orbit of hydrogen atom is given by
4 a0
8 a0
√2 a0
2 a0
The ionization energy of hydrogen atom is 13.6 eV. Following Bohr’s theory, the energy corresponding to a transition between 3rd and 4th orbit is
3.40 eV
1.51 eV
0.85 eV
0.66 eV
Hydrogen atoms are excited from ground state of the principal quantum number 4. Then the number of spectral lines observed will be
3
6
5
2
When a hydrogen atom is raised from the ground state to an excited state
potential energy decreases and kinetic energy increases
potential energy increases and kinetic energy decreases
Both kinetic energy and potential energy decrease
Absorption spectrum
Which source is associated with a line emission spectrum?
Electric fire
Neon street sign
Red traffic light
Sun
The Bohr model of atoms
assumes that the angular momentum of electrons is quantized
uses Einstein’s photoelectric equation
predict continuous emission spectra for atoms
predicts the same emission spectra for all types of atoms
