Which of the following series of emission spectral lines for hydrogen is observed in the visible region?

Calculate the frequency and wave number of a photon with a wavelength of $3.6 \ \mathring{A}$.

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

Which formula represents the rest mass of an electron?

Electromagnetic radiations of frequency $\nu$ consist of a stream of particles called photons. Which of the following statements is / are true about photons:

Assuming that the incident radiation is capable of ejecting photoelectrons from all the given metals,the lowest kinetic energy of the ejected photoelectron is observed with which of the given metals?