Calculate the frequency in $Hz$ of orange colour light having wavelength $600 \ nm$. $[c = 3 \times 10^8 \ ms^{-1}]$

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

Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength $8000 \ \mathring{A}$. What should be the maximum velocity of emitted electron when the same metal surface is exposed to radiation of wavelength $5000 \ \mathring{A}$? $\left( h = 6.6 \times 10^{-34} \ J \cdot s, \ m_e = 9.1 \times 10^{-31} \ kg, \ c = 3 \times 10^8 \ m/s \right)$

Which of the following is not an electromagnetic radiation?

Energy of a photon is $1 \ MeV,$ then its momentum will be $:-$

Calculate the wave number and frequency of orange radiation having wavelength $6300 \ \mathring{A}$.