Question

Bohr's atomic model is based on the following postulates that:

• A. an atom consists of nucleus
• B. an electron can rotate only in certain energy levels
• C. an electron remains moving with continuous loss of energy
• D. None of the above

Answer 1

Answer: (A), (B)

The correct options are
A an electron can rotate only in certain energy levels
B an atom consists of nucleus

Niels Bohr proposed, in 1913, what is now called the Bohr model of the atom. He suggested that electrons could only have certain classical motions:

1. Electrons in atoms orbit the nucleus.
2. The electrons can only orbit stably, without radiating, in certain orbits (called by Bohr the "stationary orbits") at a certain discrete set of distances from the nucleus. These orbits are associated with definite energies and are also called energy shells or energy levels.
3. Electrons can only gain and lose energy by jumping from one allowed orbit to another, absorbing or emitting electromagnetic radiation with a frequency determined by the energy difference of the levels.