When an electron moves from $L$-shell to $M$-shell,then it will be accompanied by :

Calculate the energy of an electron in the first four orbits of a hydrogen atom in $kJ \, mol^{-1}$ (Given: $N_A = 6.02 \times 10^{23} \, mol^{-1}$,Rydberg constant $R_H = 2.18 \times 10^{-18} \, J$).

Arrange the following wavelengths $(\lambda)$ of given emission lines of $H$ atoms in increasing order:
$(a) \ n = 3 \xrightarrow{\lambda_1} n = 1$
$(b) \ n = 12 \xrightarrow{\lambda_3} n = 10$
$(c) \ n = 5 \xrightarrow{\lambda_2} n = 3$
$(d) \ n = 22 \xrightarrow{\lambda_4} n = 20$
Choose the correct option.

In Bohr's model,the atomic radius of the first orbit is $\gamma$. The radius of the $3^{rd}$ orbit is:

What is the energy in joules,required to shift the electron of the hydrogen atom from the first Bohr orbit to the fifth Bohr orbit and what is the wavelength of the light emitted when the electron returns to the ground state?
The ground state electron energy is $-2.18 \times 10^{-11} \ erg$.

The number of absorption lines in the given figure will be .......