The minimum wavelength of X-rays produced by 30 kV electrons is:
(1) 0.0414 nm
(2) 0.0041 nm
(3) 0.1410 nm
An X-ray tube produces a continuous spectrum of radiation with its short wavelength end at 0.45 Å. What is the maximum energy of a photon in the radiation?
Which one of the following is not true:
(1) The sizes of the atoms taken in Thomson's model and Rutherford's model have the same order of magnitude.
(2) In the ground state of Thomson's model, the electrons are in stable equilibrium. However, in Rutherford's model, the electrons always experience a net force.
(3) A classical atom based on Thomson's model is doomed to collapse.
(4) The positively charged part of the atom possesses most of the mass in both the models.
What is the shortest wavelength present in the Paschen series of spectral lines?
1. 818.9 nm
2. 779 nm
3. 500 nm
4. 1024 nm
A difference of 2.3 eV separates two energy levels in an atom. What is the frequency of radiation emitted when the atom makes a transition from the upper level to the lower level?
The ground state energy of the hydrogen atom is –13.6 eV. What is the potential energy of the electron in this state?
(1) -13.6 eV
(2) 27.2 eV
(3) -27.2 eV
(4) 13.6 eV
The radius of the innermost electron orbit of a hydrogen atom is What is the radius of the n = 2 orbit?
A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level. The wavelength of photon is:
(1) 97 nm
(2) 99 nm
(3) 95 nm
(4) 96 nm
The speed of the electron in a hydrogen atom in the n = 1 level is:
In accordance with Bohr’s model, what is the quantum number that characterizes the earth’s revolution around the sun in an orbit of radius with orbital speed ? (Mass of earth = )