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
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
Which source is associated with a line emission spectrum?
Electric fire
Neon street sign
Red traffic light
Sun
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
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’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
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
