In which type of radiation do the mass number and atomic number remain unchanged?

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

Find the wavelength of electromagnetic radiation having frequency $1368 \ kHz$. (in $m$)

$A$ photon-sensitive metal is not emitting photoelectrons when irradiated. It will do so when the threshold is crossed. To cross the threshold,we need to increase:

Yellow light emitted from a sodium lamp has a wavelength $(\lambda)$ of $580 \,nm$. Calculate the frequency $(v)$ and wave number $(\bar{v})$ of the yellow light.

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