Which of the following travels with the speed of light?

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

Electromagnetic radiation of wavelength $663 \ nm$ is just sufficient to ionise the atom of metal $A.$ The ionization energy of metal $A$ in $kJ \ mol^{-1}$ is ...... .
(Rounded-off to the nearest integer) $\left[ h = 6.63 \times 10^{-34} \ Js, c = 3.00 \times 10^{8} \ ms^{-1}, N_{A} = 6.02 \times 10^{23} \ mol^{-1} \right]$

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 $....$.

When radiation of $300 \ nm$ is shone on five metals,namely $Li, Mg, Ag, Cu,$ and $K$,the number of metals that show the photoelectric effect is:

Give the formulas for wave number and time period.