Bohr Model of Hydrogen — Prelims Questions

An electron in a hydrogen atom makes a transition from an orbit with principal quantum number $n_i = 4$ to $n_f = 2$. What is the wavelength of the emitted photon? (Given: Rydberg constant $R_H = 1.097 \times 10^7,\text{m}^{-1}$)

According to Bohr's model, the radius of the $n$-th orbit of a hydrogen atom is proportional to:

The total energy of an electron in the $n$-th stationary orbit of the hydrogen atom is proportional to:

What is the ratio of the speed of an electron in the first Bohr orbit of a hydrogen atom to the speed of light in vacuum ($c$)? (Given: $e = 1.6 \times 10^{-19},\text{C}$, $h = 6.63 \times 10^{-34},\text{J s}$, $epsilon_0 = 8.85 \times 10^{-12},\text{F/m}$, $c = 3 \times 10^8,\text{m/s}$)

Which of the following statements is NOT a postulate of Bohr's model of the atom?

The ratio of the kinetic energy to the total energy of an electron in a Bohr orbit is: