Calculate the wavelength for the emission of a photon having a wave number of $11516 \ cm^{-1}$. (in $nm$)

Fill in the blanks:
$(i)$ If the orbits around the nucleus contract,the electron will spiral into the nucleus in $....$ seconds.
$(ii)$ Waves used in radio broadcasting have a frequency of $....$ $Hz$.
$(iii)$ The $SI$ unit of frequency is $....$.
$(iv)$ The number of waves present in unit length is called $....$.

The energy of one mole of photons of radiation of frequency $2 \times 10^{12} \ Hz$ in $J \ mol^{-1}$ is $.....$ (Nearest integer) (Given: $h = 6.626 \times 10^{-34} \ Js$,$N_A = 6.022 \times 10^{23} \ mol^{-1}$)

Assertion : Absorption spectrum consists of some bright lines separated by dark spaces.
Reason : Emission spectrum consists of dark lines.

The frequency of a radio station of All India Radio is $1368 \, kHz$. The wavelength of the electromagnetic waves emitted by the transmitter is ............... $m$.

Give the characteristics of electromagnetic radiation. Give the relation between them.