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 a0 is the radius of the ground state orbit, m is the mass and e is the charge on the electron, ε0 is the vacuum permittivity, the speed of the electron is
Zero
If the electron in a hydrogen atom jumps from an orbit with level n2 = 3 to an orbit with level n1 = 2, the emitted radiation has a wavelength given by
λ = 6/R
λ = R/6
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
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
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
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
Which of the following transitions in a hydrogen atom emits of the highest frequency?
n = 1 to n = 2
n = 2 to n = 6
n = 2 to n = 1
n = 6 to n = 2
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
The energy required to excite hydrogen atom from n = 1 to n = 2 state is 10.2 eV. What is the wavelength emitted when it returns to ground state?
1020 × 10-10 m
1220 × 10-10 m
1320 × 10-10 m
920 × 10-10 m
The total energy of electron in the ground state of hydrogen atom is -13.6 eV. The kinetic energy of an electron in the first excited state is
3.4 eV
6.8 eV
13.6 eV
1.7 eV