Question

Bohr’s model can explain:
(A) the spectrum of hydrogen atom only
(B) a spectrum of an atom or ion containing one electron only
(C) the spectrum of hydrogen only
(D) the solar spectrum

Answer 1

Hint: Regarding the structure of atoms and molecules, their interaction of radiations with the matter has provided more information. Neils Bohr utilized this information to improve a model proposed by Rutherford. The dual character of electromagnetic radiation and atomic spectra are two important developments that played an important role in the formulation of Bohr’s model of the atom.

Complete step by step solution:
The general features of the hydrogen atom and its spectrum are quantitatively explained in Bohr’s model for a hydrogen atom. This model explained on basis of the following postulates:
(1) The electron in the hydrogen atom can move around the nucleus in a circular path of fixed radius and energy, which paths are known as orbits, stationary states, or allowed energy states. These orbits are arranged around the nucleus based on their energy.
(2) The energy of an electron in the orbit does not change with time. When the required amount of energy is absorbed by electron or energy emitted by electron, then electron moves from a lower stationary state to a higher energy state.
(3) When a transition occurs between two different energy states, then the frequency of energy emitted or absorbed is,
$v={\displaystyle \frac{\mathrm{\Delta }E}{h}}$
The spectral lines of atomic hydrogen

Name	$n_1$	$n_2$	Spectral region
Lyman	1	2, 3, 4…	Ultraviolet
Balmer	2	3, 4, 5, ..	Visible
Paschen	3	4, 5…	Infrared
Brackett	4	5,6 …	Infrared
Pfund	5	6, 7 …	Infrared

Bohr’s theory can apply only one electron, similar to that present in the hydrogen atom.
Hence, Bohr’s model explains the spectrum of an atom or ion containing one electron only.

So, the correct option is B.

Note: Bohr’s model applied only hydrogen-like ions. For example, $H{e}^{+},L{i}^{+2},B{e}^{+3}$ , and so on. This model fails to explain the spectra of atoms or ions having two or more electrons. It could not explain the ability of atoms to form molecules by chemical bonds.