If the electron of a hydrogen atom is in the third orbit,it represents its ...... excited state.

The ratio of the time period of an electron in the first and third orbit of an $H$-atom would be:

The correct representation of the wavelength-intensity relationship of an ideal black body radiation at two different temperatures $T_{1}$ and $T_{2}$ (where $T_{2} > T_{1}$) 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 $-2.18 \times 10^{-11} \ erg$.

Angular momentum of an electron in the $n^{th}$ orbit of a hydrogen atom is given by

The ratio of the energy of a photon of $2000 \ \mathring{A}$ wavelength radiation to that of $4000 \ \mathring{A}$ radiation is