The watermelon model of the atom was proposed by:

The electrostatic force of attraction between the electron and the nucleus in a hydrogen atom is given by:

For an emission line of atomic hydrogen from $n_i = 8$ to $n_f = n$,the plot of wave number $(\bar{\nu})$ against $(\frac{1}{n^2})$ will be (The Rydberg constant,$R_H$ is in wave number unit).

The energy of the orbit of hydrogen is $E_n = \frac{1.31 \times 10^6}{n^2} \ J \ mol^{-1}$. If an electron transits from $n = 3$ to $n = 2$,find the frequency of the emitted radiation. (Note: $h = 6.6 \times 10^{-34} \ J \ s$,$N_A = 6.02 \times 10^{23} \ mol^{-1}$)

Calculate the energy associated with the third orbit of $He^{+}$.

The ratio of the energy of the electrons in the ground state of hydrogen to the electrons in the first excited state of $Be^{3+}$ is: