The work function of a metal is .........

With reference to the observations in photoelectric effect,identify the correct statements from below:
$A.$ The square of maximum velocity of photoelectrons varies linearly with frequency of incident light.
$B.$ The value of saturation current increases on moving the source of light away from the metal surface.
$C.$ The maximum kinetic energy of photoelectrons decreases on decreasing the power of $LED$ (light emitting diode) source of light.
$D.$ The immediate emission of photoelectrons out of metal surface can not be explained by particle nature of light/electromagnetic waves.
$E.$ Existence of threshold wavelength can not be explained by wave nature of light/electromagnetic waves.
Choose the correct answer from the options given below:

The retarding potential for having zero photo-electron current:

The photoelectric threshold wavelength for a certain metal surface is $3600 \mathring A$. If the metal surface is irradiated by a wavelength of $1100 \mathring A$,the kinetic energy of the emitted photoelectrons is (in $\text{ eV}$)

In the case of the photoelectric effect,the graph of measured stopping potential $(V_0)$ against the frequency $(\nu)$ of incident light is a straight line. The slope of this line multiplied by the charge of an electron $(e)$ gives:

The frequency of incident light falling on a photosensitive material is doubled. The kinetic energy $(K.E.)$ of the emitted photoelectrons will be: