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
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 a Rutherford scattering experiment when a projectile of charge Z1and mass M1 approaches a target nucleus of charge Z2 and Mass M2, the distance of closest approach is r0. The energy of the projectile is
directly proportional to M1 × M2
directly proportional to Z1 Z2
inversely proportional to Z1
directly proportional to Mass M1
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
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
When hydrogen atom is in its first excited level, its radius is
four times, its ground sate radius
twice, its ground state radius
same as its ground state radius
half of its ground state radius
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
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
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
