In Bohr's model of the hydrogen atom,which of the following pairs of quantities are quantized?

Write the theoretical value and experimental value of the Rydberg constant,including the unit.

Find the radius of $Be^{3+}$ ions in its ground state assuming Bohr's model to be valid $(a_0 = 53 \ pm)$. (in $pm$)

According to de-Broglie,the de-Broglie wavelength for an electron in an orbit of radius $5.3 \times 10^{-11} \ m$ of a hydrogen atom is $10^{-10} \ m$. The principal quantum number for this electron is:

When an electron is excited from its $4^{\text{th}}$ orbit to its $5^{\text{th}}$ stationary orbit,the change in the angular momentum of the electron is approximately (Planck's constant $= h = 6.63 \times 10^{-34} \text{ J s}$)

The radius of orbit of an electron and the speed of an electron in the ground state of a hydrogen atom are $5.5 \times 10^{-11} \,m$ and $4 \times 10^6 \,m/s$ respectively. Then,the orbital period of this electron in the first excited state will be