In an experiment on photo electric effect, how does stopping potential change, if at all, when…

In an experiment on photo electric effect, how does stopping potential change, if at all, when intensity of incident monochromatic UV radiation is increased?

Ultraviolet light is incident on metals P, Q and R, having work functions $8\text{ eV}$, $2\text{ eV}$ and $4\text{ eV}$ respectively. (a) Which metal has lowest threshold frequency for photoelectric effect? (b) For which metal is the value of $E_{\max}$ minimum? (Note: $E_{\max}$ is maximum kinetic energy of the emitted photoelectrons.)