Mercury street lights emit light of a pale blue color with a wavelength of $436 \, nm$. Calculate its frequency.

It is observed that characteristic $X$-ray spectra of elements show regularity. When frequency to the power '$n$' i.e.,$v^{n}$ of $X$-rays emitted is plotted against atomic number '$Z$',the following graph is obtained. The value of '$n$' is

$750$ waves of an electromagnetic radiation pass a point in one minute. What is the wavelength of the radiation?

Which of the following sets of radiations cannot be seen in the hydrogen atomic spectrum? $(i)$ $\gamma$-radiation $(ii)$ $UV$ $(iii)$ $X$-rays $(iv)$ Infrared

With regard to the photoelectric effect,identify the correct statement among the following.

Find the energy of radiation having $7000 \ \mathring{A}$ and $400 \ nm$ wavelength. $\left( h = 6.62 \times 10^{-34} \ J \ s, c = 3 \times 10^8 \ m/s \right)$