The wavelength of $X$-ray is $1.5 \times 10^{-10} \ m$. Find the frequency.

The energy of an electromagnetic radiation is $19.875 \times 10^{-13} \ erg$. What is its wave number in $cm^{-1}$? $(h = 6.625 \times 10^{-27} \ erg \ sec, c = 3 \times 10^{10} \ cm \ sec^{-1})$

The energy of one mole of photons of radiation of wavelength $300 \ nm$ is ...... $kJ \ mol^{-1}$. (Given: $h = 6.63 \times 10^{-34} \ J \ s, N_A = 6.02 \times 10^{23} \ mol^{-1}, c = 3 \times 10^8 \ m \ s^{-1}$)

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

Which properties characterize electromagnetic radiation?

Which of the following coloured light has the highest energy?