Which of the following activities can be compared to the concept of quantisation?

The kinetic energy of an electron in the ground state of a $Be^{3+}$ ion is given by:

The radius of the second Bohr orbit for hydrogen atom is .......... $\mathring{A}$.
(Planck's constant $h = 6.626 \times 10^{-34} \, Js$; mass of electron $= 9.1091 \times 10^{-31} \, kg$; charge of electron $e = 1.60210 \times 10^{-19} \, C$; permittivity of vacuum $\epsilon_0 = 8.854185 \times 10^{-12} \, C^2 N^{-1} m^{-2}$)

The total energy of the electron of $H^{-}$ atom in the second quantum state is $-E_2$. The total energy of the $He^{+}$ atom in the third quantum state is

In the Bohr model of an atom, the radius of a hydrogen atom in the ground state is $r_1$ and the radius of a $He^{+}$ ion in the ground state is $r_2$. Which of the following is correct?

The ground state energy of hydrogen atom is $-13.6 \ eV$. The energy of the second excited state of $He^{+}$ ion in $eV$ is: