Who proposed the model of the atom in which **electrons revolve in fixed orbits** around the nucleus?
Analysis & Theory
Niels Bohr proposed the planetary model with electrons in discrete orbits in 1913.
According to Bohr’s model, electrons revolve around the nucleus in:
C
Fixed circular paths called energy levels
Analysis & Theory
Bohr stated that electrons move in fixed circular orbits, also known as shells or energy levels.
In Bohr’s model, each orbit is associated with a fixed:
Analysis & Theory
Each orbit or energy level has a specific energy, and electrons do not lose energy while in that orbit.
What happens when an electron **jumps from a higher energy level to a lower one**?
B
The atom becomes unstable
C
Energy is emitted as radiation
Analysis & Theory
Energy is released in the form of electromagnetic radiation when electrons drop to lower levels.
Bohr’s model explained the line spectra of which element successfully?
Analysis & Theory
Bohr’s model accurately explained the line spectra of hydrogen, a one-electron system.
Which of the following is a **limitation** of Bohr’s model?
A
It cannot explain the stability of atoms
B
It does not define electrons
C
It fails for multi-electron atoms
Analysis & Theory
Bohr’s model works only for single-electron systems like hydrogen, not for complex atoms.
The energy of orbits in Bohr’s model is:
Analysis & Theory
Electrons can only occupy certain energy levels, and the energies are quantized.
In Bohr’s model, what is the principal quantum number (n)?
A
It represents angular momentum
B
It indicates the shape of the orbit
C
It denotes the energy level or shell
D
It defines spin direction
Analysis & Theory
The principal quantum number (n = 1, 2, 3...) represents the main energy levels of the atom.
According to Bohr, the angular momentum of an electron is:
A
Half-integer multiple of h
B
An integer multiple of h/2π
Analysis & Theory
Bohr proposed that angular momentum is quantized as: mvr = n(h/2π), where n is an integer.
Which constant is used in Bohr’s angular momentum quantization condition?
Analysis & Theory
Planck’s constant (h) is used in the quantization of angular momentum: mvr = nh/2π.