The radius of the orbit of an electron in a $H$-atom changes from $2.12 \mathring{A}$ to $4.77 \mathring{A}$. The $H$-atom has:

In the Bohr model,an electron moves in a circular orbit around the nucleus. Considering an orbiting electron to be a circular current loop,the magnetic moment of the hydrogen atom,when the electron is in the $n^{th}$ excited state,is ($e=$ electronic charge,$m_{e}=$ mass of the electron,$h=$ Planck's constant).

$A$ monochromatic radiation of wavelength $\lambda$ is incident on a hydrogen sample in ground state. The sample subsequently emits radiation of six different wavelengths, then the value of $\lambda$ is. [Use $hc = 1242 \text{ eV-nm}$] (in $\text{ nm}$)

The ionisation energy of $10$ times ionised sodium atom is:

An electron in Bohr's hydrogen atom has an energy of $-3.4 \ eV$. The angular momentum of the electron is

In the Bohr model of the hydrogen atom,let $R, v$,and $E$ represent the radius of the orbit,the speed of the electron,and the total energy of the electron,respectively. Which of the following quantities is proportional to the quantum number $n$?